Anionic and Magnetic Ordering in Rare Earth Tantalum Oxynitrides with an n = 1 Ruddlesden-Popper Structure.

The new compounds R2TaO4-xNx with R = La, Ce, Nd, and Eu and 1.20 ≤ x ≤ 2.81 have been obtained by a solid-state reaction between metal nitrides and oxides or oxynitrides under N2 gas at temperatures between 1200 and 1700 °C. They are the first examples of rare earth transition metal oxynitrides with an n = 1 Ruddlesden-Popper structure and show different anion stoichiometries, crystal structures, and magnetic properties. Synchrotron X-ray powder diffraction and electron diffraction indicate that the lanthanum, cerium, and neodymium compounds crystallize in the orthorhombic space group Pccn, with cell parameters a = 5.72949(2), b = 5.73055(5), and c = 12.77917(6) Å for La2TaO1.31N2.69, a = 5.70500(5), b = 5.71182(4), and c = 12.61280(7) Å for Ce2TaO1.19N2.81, and a = 5.70466(3), b = 5.70476(5), and c = 12.32365(5) Å for Nd2TaO1.46N2.54. In contrast, Eu2TaO2.80N1.20 shows a tetragonal I41/acd superstructure doubling the c axis, with parameters a = 5.71867(2) and c = 25.00092(19) Å. Refinement of neutron powder diffraction data of Ce2TaO1.19N2.81 indicated the nitrogen order in the two equatorial positions of the tantalum octahedron, with refined N/O occupancies of 0.930(7)/0.070 and 0.876(13)/0.124, and the axial position is occupied by 50% of each anion. This anion ordering agrees with the distribution predicted by Pauling's second crystal rule. Magnetization measurements show that the cerium and europium compounds are ordered magnetically at low temperatures, while the neodymium compound remains paramagnetic down to 2 K, as a consequence of suppression of the effective magnetic moment of the latter when reducing the temperature.

Robust Antiferromagnetic FeRh Films on Mica.

FeRh shows an antiferromagnetic to ferromagnetic phase transition above room temperature, which permits its use as an antiferromagnetic memory element. However, its antiferromagnetic order is sensitive to small variations in crystallinity and composition, challenging its integration into flexible devices. Here, we show that flexible FeRh films of high crystalline quality can be synthesized by using mica as a substrate, followed by a mechanical exfoliation of the mica. The magnetic and transport data indicate that the FeRh films display a sharp antiferromagnetic to ferromagnetic phase transition. Magnetotransport data allow for the observation of two distinguishable resistance states, which are written after a field-cooling procedure. It is shown that the memory states are robust under the application of magnetic fields of up to 10 kOe.

High-Temperature Synthesis of Ferromagnetic Eu3Ta3(O,N)9 with a Triple Perovskite Structure.

Europium tantalum perovskite oxynitrides were prepared by a new high-temperature solid-state synthesis under N2 or N2/H2 gas. The nitrogen stoichiometry was tuned from 0.63 to 1.78 atoms per Eu or Ta atom, starting with appropriate N/O ratios in the mixture of the reactants Eu2O3, EuN and Ta3N5, or Eu2O3 and TaON, which was treated at 1200 °C for 3 h. Two phases were isolated with compositions EuTaO2.37N0.63 and Eu3Ta3O3.66N5.34, showing different crystal structures and magnetic properties. Electron diffraction and Rietveld refinement of synchrotron radiation X-ray diffraction indicated that EuTaO2.37N0.63 is a simple perovskite with cubic Pm3̅m structure and cell parameter a = 4.02043(1) Å, whereas the new compound Eu3Ta3O3.66N5.34 is the first example of a triple perovskite oxynitride and shows space group P4/mmm with crystal parameters a = 3.99610(2), c = 11.96238(9) Å. The tripling of the c-axis in this phase is a consequence of the partial ordering of europium atoms with different charges in two A sites of the perovskite structure with relative ratio 2:1, where the formal oxidation states +3 and +2 are respectively dominant. Magnetic data provide evidence of ferromagnetic ordering developing at low temperatures in both oxynitrides, with saturation magnetization of about 6 µB and 3 µB per Eu ion for EuTaO2.37N0.63 and the triple perovskite Eu3Ta3O3.66N5.34 respectively, and corresponding Curie temperatures of about 7 and 3 K, which is in agreement with the lower proportion of Eu2+ in the latter compound.

Ferroelectric Electroresistance after a Breakdown in Epitaxial Hf0.5Zr0.5O2 Tunnel Junctions.

The recent discovery of ferroelectricity in doped HfO2 has opened perspectives on the development of memristors based on ferroelectric switching, including ferroelectric tunnel junctions. In these devices, conductive channels are formed in a similar manner to junctions based on nonferroelectric oxides. The formation of the conductive channels does not preclude the presence of ferroelectric switching, but little is known about the device ferroelectric properties after conduction path formation or their impact on the electric modulation of the resistance state. Here, we show that ferroelectricity and related sizable electroresistance are observed in pristine 4.6 nm epitaxial Hf0.5Zr0.5O2 (HZO) tunnel junctions grown on Si. After a soft breakdown induced by the application of suitable voltage, the resistance decreases by about five orders of magnitude, but signatures of ferroelectricity and electroresistance are still observed. Impedance spectroscopy allows us to conclude that the effective ferroelectric device area after the breakdown is reduced, most likely by the formation of conducting paths at the edge.

Control of up-to-down/down-to-up light-induced ferroelectric polarization reversal.

Light control of ferroelectric polarization is of interest for the exploitation of ferroelectric thin films in ultrafast data storage and logic functionalities. The rapidly oscillating electric field of light absorbed in a ferroelectric layer can suppress its polarization but cannot selectively reverse its direction. Here we take advantage of the built-in asymmetry at ferroelectric/electrode interfaces to break the up/down symmetry in uniaxial ferroelectrics to promote polarization reversal under illumination. It is shown that appropriate ferroelectric/metal structures allow the direction of the imprint electric field to be selected, which is instrumental for polarization reversal. This ability is further exploited by demonstrating the optical control of the resistance states in a ferroelectric capacitor.

High-Temperature Synthesis and Dielectric Properties of LaTaON2.

The development of new synthetic methodologies of perovskite oxynitrides is challenging but necessary for the search of new compounds and the investigation of new properties. Here, we report a new method of preparation of the perovskite LaTaON2 that has been investigated as a pigment and photocatalyst for water splitting. The synthesis proceeds through the solid-state reactions under N2 at 1500 °C between La2O3, LaN, and Ta3N5 or between LaN and TaON, which are completed after 3 h and lead to sintered, highly crystalline samples with particle sizes up to 1 µm. Nitrogen-deficient samples LaTaO1+xN2-x with x ≤ 0.35 are prepared by changing the N/O ratio in the mixture of reactants. Electron diffraction, synchrotron diffraction, and neutron diffraction studies on stoichiometric and nitrogen-deficient compounds indicate that they crystallize in the monoclinic space group I2/m with lattice parameters for LaTaON2 of a = 5.71458(7), b = 8.05987(10), c = 5.74772(6) Å, and ß = 89.982(3)°. The three anion sites of the I2/m structure are partially occupied by oxygen and nitrogen, with a preference of nitride for two positions with occupancies of 77 and 88%. This anion distribution is different from that reported in previous studies of samples prepared by ammonolysis at lower temperature, suggesting that the synthesis conditions affect the anion order of this perovskite. Optical measurements indicate a band gap of about 1.9 eV, which is close to that observed in samples prepared by other methods. The determined dielectric permittivity for LaTaON2 εr ≈ 200, reported for the first time for a highly nitrided pseudocubic perovskite, is similar to that observed in perovskites with one nitrogen per formula.

Electron-Phonon Coupling and Electron-Phonon Scattering in SrVO3.

Understanding the physics of strongly correlated electronic systems has been a central issue in condensed matter physics for decades. In transition metal oxides, strong correlations characteristic of narrow d bands are at the origin of remarkable properties such as the opening of Mott gap, enhanced effective mass, and anomalous vibronic coupling, to mention a few. SrVO3 with V4+  in a 3d1  electronic configuration is the simplest example of a 3D correlated metallic electronic system. Here, the authors' focus on the observation of a (roughly) quadratic temperature dependence of the inverse electron mobility of this seemingly simple system, which is an intriguing property shared by other metallic oxides. The systematic analysis of electronic transport in SrVO3  thin films discloses the limitations of the simplest picture of e-e correlations in a Fermi liquid (FL); instead, it is shown show that the quasi-2D topology of the Fermi surface (FS) and a strong electron-phonon coupling, contributing to dress carriers with a phonon cloud, play a pivotal role on the reported electron spectroscopic, optical, thermodynamic, and transport data. The picture that emerges is not restricted to SrVO3  but can be shared with other 3d and 4d metallic oxides.

Impacto de la formación en entrevista motivacional para médicos: diseño y evaluación de un Programa Formativo (MOTIVA) / Impact of training on Motivational Interviewing (MI) for Family Physicians: Design and assessment of a Training Program (MOTIVA)

Objetivo: Desarrollar un programa de formación en Entrevista Motivacional (EM) para Médicos de Familia y evaluar el impacto. Diseño: Ensayo clínico multicéntrico a doble ciego y aleatorizado, con 2 ramas (experimental (GE) y control (GC)) de Médicos de Familia, con un seguimiento de 12 meses. Emplazamiento: 32 Centros de Atención Primaria. Descripción de la muestra: 54 médicos (GC = 28, GE = 26). Intervenciones: Programa de formación MOTIVA en EM con un curso presencial inicial (16 h), seguido de actividades en línea durante 12 meses y reuniones presenciales (entrevistas basadas en problemas con feedback de expertos). Medidas principales: las habilidades comunicativas en EM se evaluaron en base a videograbaciones (VG) con la escala EVEM 2.0, por parejas de revisores. Se analizaron 236 VG con pacientes estandarizados y 96 VG con pacientes reales. Resultados: Los resultados promedio en la escala EVEM (hasta 56 puntos) al inicio del estudio fueron GE = 21,27 (IC 95% 15,8-26,7) y GC = 20,23 (IC95% 16,4-23,9) sin diferencias entre ambos grupos (p = 0,79). Después del curso, la puntuación GE aumentó en 13,89 puntos (P <0,001), promedio 35,16 (IC 95% 29,8-40,6). Las VG de pacientes reales en GE durante el periodo de 12 meses mantiene sus habilidades en EM con un promedio de 36,9 puntos (IC 95% 30,3-43,6) versus GC 15,9 puntos (IC 95% 9,8-22,0). Una vez finalizado el Programa de Formación MOTIVA, el GE mantiene las habilidades adquiridas: GE promedio final = 37.6 (IC 95% 33.2-41.1) versus GC = 24,3 (IC95% 19,0-29,2) (p <0,001). Conclusiones: El Programa de Formación MOTIVA mejora significativamente las habilidades de entrevista motivacional, mejorando después de un curso presencial y actividades secuenciales de mantenimiento. La eficacia del programa ha sido probada en el tercer y cuarto escalón de la Pirámide de Miller.(AU)

Aim: To develop a training program in Motivational Interviewing for Family Physicians and assess the impact. Study design: Multicenter, double blind and randomized clinical essay, with 2arms, Experimental (EG) and Control (CG) of Family Physicians with a follow up of 12 months. Location: 32 Primary Healthcare Centers. Sample description: 54 physicians (CG=28, EG=26). Interventions: Training Program MOTIVA in ME with an initial presential course (16h), followed by online activities during 12months, and presential meetings (Problem BasedInterviewing with expert feedback). Main measurements: Communicative skills in MI were assessed based on video-recordings (VR) with the EVEM 2.0 scale by peer reviewers. 236 VR with standardized patients and 96 VR with real patients. Results: Average results in EVEM scale (up to 56 points) at the beginning of the study were EG=21.27 (CI 95% 15.8-26.7) and CG=20.23 (CI95% 16.4-23.9) with no differences between both groups (P=.79). After the training, EG punctuation increased by 13.89 points (P<.001), average 35.16 (CI 95% 29.8-40.6). Real patients’ VR in EG over a 12 month period keep their MI skills with an average of 36.9 points (CI 95% 30.3-43.6) versus CG 15.9 points (CI 95% 9.8-22.0). Once ended the MOTIVA Training Program, the EG maintains the acquired skills: final average EG=37.6 (CI 95% 33.2-41.1) versus CG=24.3 (CI95% 19.0-29.2) (P<.001). Conclusions: The MOTIVA Training Program improves Motivational Interviewing skills, significatively improving after a presential course and sequential keep-alive activities. The effectiveness of the Program has been proven in the Third and Fourth steps of Miller's Pyramid.(AU)

[Impact of training on Motivational Interviewing (MI) for Family Physicians: Design and assessment of a Training Program (MOTIVA)]. / Impacto de la formación en entrevista motivacional para médicos: diseño y evaluación de un Programa Formativo (MOTIVA).

AIM: To develop a training program in Motivational Interviewing for Family Physicians and assess the impact. STUDY DESIGN: Multicenter, double blind and randomized clinical essay, with 2arms, Experimental (EG) and Control (CG) of Family Physicians with a follow up of 12 months. LOCATION: 32 Primary Healthcare Centers. SAMPLE DESCRIPTION: 54 physicians (CG=28, EG=26). INTERVENTIONS: Training Program MOTIVA in ME with an initial presential course (16h), followed by online activities during 12months, and presential meetings (Problem BasedInterviewing with expert feedback). MAIN MEASUREMENTS: Communicative skills in MI were assessed based on video-recordings (VR) with the EVEM 2.0 scale by peer reviewers. 236 VR with standardized patients and 96 VR with real patients. RESULTS: Average results in EVEM scale (up to 56 points) at the beginning of the study were EG=21.27 (CI 95% 15.8-26.7) and CG=20.23 (CI95% 16.4-23.9) with no differences between both groups (P=.79). After the training, EG punctuation increased by 13.89 points (P<.001), average 35.16 (CI 95% 29.8-40.6). Real patients' VR in EG over a 12 month period keep their MI skills with an average of 36.9 points (CI 95% 30.3-43.6) versus CG 15.9 points (CI 95% 9.8-22.0). Once ended the MOTIVA Training Program, the EG maintains the acquired skills: final average EG=37.6 (CI 95% 33.2-41.1) versus CG=24.3 (CI95% 19.0-29.2) (P<.001). CONCLUSIONS: The MOTIVA Training Program improves Motivational Interviewing skills, significatively improving after a presential course and sequential keep-alive activities. The effectiveness of the Program has been proven in the Third and Fourth steps of Miller's Pyramid.

Non-volatile optical switch of resistance in photoferroelectric tunnel junctions.

In the quest for energy efficient and fast memory elements, optically controlled ferroelectric memories are promising candidates. Here, we show that, by taking advantage of the imprint electric field existing in the nanometric BaTiO3 films and their photovoltaic response at visible light, the polarization of suitably written domains can be reversed under illumination. We exploit this effect to trigger and measure the associate change of resistance in tunnel devices. We show that engineering the device structure by inserting an auxiliary dielectric layer, the electroresistance increases by a factor near 2 × 103%, and a robust electric and optic cycling of the device can be obtained mimicking the operation of a memory device under dual control of light and electric fields.

Effectiveness and cost-effectiveness of a virtual community of practice to improve the empowerment of patients with ischaemic heart disease: study protocol of a randomised controlled trial.

INTRODUCTION: Virtual Communities of Practice (VCoP) or knowledge-sharing virtual communities offer ubiquitous access to information and exchange possibilities for people in similar situations, which might be especially valuable for the self-management of patients with chronic diseases. In view of the scarce evidence on the clinical and economic impact of these interventions on chronic conditions, we aim to evaluate the effectiveness and cost-effectiveness of a VCoP in the improvement of the activation and other patient empowerment measures in patients with ischaemic heart disease (IHD). METHODS AND ANALYSIS: A pragmatic randomised controlled trial will be performed in Catalonia, Madrid and Canary Islands, Spain. Two hundred and fifty patients with a recent diagnosis of IHD attending the participating centres will be selected and randomised to the intervention or control group. The intervention group will be offered participation for 12 months in a VCoP based on a gamified web 2.0 platform where there is interaction with other patients and a multidisciplinary professional team. Intervention and control groups will receive usual care. The primary outcome will be measured with the Patient Activation Measure questionnaire at baseline, 6, 12 and 18 months. Secondary outcomes will include: clinical variables; knowledge (Questionnaire of Cardiovascular Risk Factors), attitudes (Self-efficacy Managing Chronic Disease Scale), adherence to the Mediterranean diet (Mediterranean Diet Questionnaire), level of physical activity (International Physical Activity Questionnaire), depression (Patient Health Questionnaire), anxiety (Hospital Anxiety Scale-A), medication adherence (Adherence to Refill Medication Scale), quality of life (EQ-5D-5L) and health resources use. Data will be collected from self-reported questionnaires and electronic medical records. ETHICS AND DISSEMINATION: The trial was approved by Clinical Research Ethics Committee of Gregorio Marañón University Hospital in Madrid, Nuestra Señora de Candelaria University Hospital in Santa Cruz de Tenerife and IDIAP Jordi Gol in Barcelona. The results will be disseminated through workshops, policy briefs, peer-reviewed publications, local/international conferences. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT03959631). Pre-results.

Engineering Polar Oxynitrides: Hexagonal Perovskite BaWON2.

Non-centrosymmetric polar compounds have important technological properties. Reported perovskite oxynitrides show centrosymmetric structures, and for some of them high permittivities have been observed and ascribed to local dipoles induced by partial order of nitride and oxide. Reported here is the first hexagonal perovskite oxynitride BaWON2 , which shows a polar 6H polytype. Synchrotron X-ray and neutron powder diffraction, and annular bright-field in scanning transmission electron microscopy indicate that it crystalizes in the non-centrosymmetric space group P63 mc, with a total order of nitride and oxide at two distinct coordination environments in cubic and hexagonal packed BaX3 layers. A synergetic second-order Jahn-Teller effect, supported by first principle calculations, anion order, and electrostatic repulsions between W6+ cations, induce large distortions at two inequivalent face-sharing octahedra that lead to long-range ordered dipoles and spontaneous polarization along the c axis. The new oxynitride is a semiconductor with a band gap of 1.1 eV and a large permittivity.

Flexible Antiferromagnetic FeRh Tapes as Memory Elements.

The antiferromagnetic to ferromagnetic transition occurring above room temperature in FeRh is attracting interest for applications in spintronics, with perspectives for robust and untraceable data storage. Here, we show that FeRh films can be grown on a flexible metallic substrate (tape shaped), coated with a textured rock-salt MgO layer, suitable for large-scale applications. The FeRh tape displays a sharp antiferromagnetic to ferromagnetic transition at about 90 °C. Its magnetic properties are preserved by bending (radii of 300 mm), and their anisotropic magnetoresistance (up to 0.05%) is used to illustrate data writing/reading capability.

Complementary Resistive Switching Using Metal-Ferroelectric-Metal Tunnel Junctions.

Complementary resistive switching (CRS) devices are receiving attention because they can potentially solve the current-sneak and current-leakage problems of memory arrays based on resistive switching (RS) elements. It is shown here that a simple anti-serial connection of two ferroelectric tunnel junctions, based on BaTiO3 , with symmetric top metallic electrodes and a common, floating bottom nanometric film electrode, constitute a CRS memory element. It allows nonvolatile storage of binary states ("1" = "HRS+LRS" and "0" = "LRS+HRS"), where HRS (LRS) indicate the high (low) resistance state of each ferroelectric tunnel junction. Remarkably, these states have an identical and large resistance in the remanent state, characteristic of CRS. Here, protocols for writing information are reported and it is shown that non-destructive or destructive reading schemes can be chosen by selecting the appropriate reading voltage amplitude. Moreover, this dual-tunnel device has a significantly lower power consumption than a single ferroelectric tunnel junction to perform writing/reading functions, as is experimentally demonstrated. These findings illustrate that the recent impressive development of ferroelectric tunnel junctions can be further exploited to contribute to solving critical bottlenecks in data storage and logic functions implemented using RS elements.

Topochemical nitridation of Sr2FeMoO6.

The topotactic nitridation of cation ordered, tetragonal Sr2FeMoO6 in NH3 at moderate temperatures leads to cubic, Fm3[combining macron]m double perovskite oxynitride Sr2FeMoO4.9N1.1 where double-exchange interactions determine ferromagnetic order with TC ≈ 100 K. Substitution of oxide by nitride induces bond asymmetries and local electronically driven structural distortions, which combined with Fermi level lowering restricts charge itinerancy to confined regions and preclude spontaneous long-range magnetic order. Under a magnetic field, ferromagnetic correlations expand, favoring charge delocalization and a negative magnetoresistance is observed.

Epitaxial Integration on Si(001) of Ferroelectric Hf0.5Zr0.5O2 Capacitors with High Retention and Endurance.

Epitaxial ferroelectric Hf0.5Zr0.5O2 films have been successfully integrated in a capacitor heterostructure on Si(001). The orthorhombic Hf0.5Zr0.5O2 phase, [111] out-of-plane oriented, is stabilized in the films. The films present high remnant polarization Pr close to 20 µC/cm2, rivaling with equivalent epitaxial films on single crystalline oxide substrates. Retention time is longer than 10 years for a writing field of around 5 MV/cm, and the capacitors show endurance up to 109 cycles for a writing voltage of around 4 MV/cm. It is found that the formation of the orthorhombic ferroelectric phase depends critically on the bottom electrode, being achieved on La0.67Sr0.33MnO3 but not on LaNiO3. The demonstration of excellent ferroelectric properties in epitaxial films of Hf0.5Zr0.5O2 on Si(001) is relevant toward fabrication of devices that require homogeneity in the nanometer scale, as well as for better understanding of the intrinsic properties of this promising ferroelectric oxide.

Control of Polar Orientation and Lattice Strain in Epitaxial BaTiO3 Films on Silicon.

Conventional strain engineering of epitaxial ferroelectric oxide thin films is based on the selection of substrates with a suitable lattice parameter. Here, we show that the variation of oxygen pressure during pulsed laser deposition is a flexible strain engineering method for epitaxial ferroelectric BaTiO3 films either on perovskite substrates or on Si(001) wafers. This unconventional growth strategy permits continuous tuning of strain up to high levels (ε > 0.8%) in films greater than one hundred nanometers thick, as well as selecting the polar axis orientation to be either parallel or perpendicular to the substrate surface plane.

Control of the Polarization of Ferroelectric Capacitors by the Concurrent Action of Light and Adsorbates.

Ferroelectric perovskites hold promise of enhanced photovoltaic efficiency and photocatalytic activity. Consequently, the photoresponse of oxide ferroelectric thin films is an active field of research. In electrode/ferroelectric/electrode devices, internal charge in the ferroelectric, free charge in the electrodes, and buried adsorbates at interfaces combine to screen the ferroelectric polarization and to stabilize the polar state. Under illumination, photoinduced carriers and photodissociated adsorbates may disrupt the screening equilibrium, modifying the switchable polarization and altering its expected benefits. Here, we explore the photoresponse of BaTiO3 thin films in a capacitor geometry, focusing on the effects of visible illumination on the remanent polarization. By combining ferroelectric and X-ray photoelectron spectroscopy, we discover that photoreaction of charge-screening H2O-derived adsorbates at the buried metal-ferroelectric Pt/BaTiO3 interface plays an unexpected pivotal role, enabling a substantial modulation (up to 75%) of the switchable remanent polarization by light. These findings illustrate that the synergy between photochemistry and photovoltaic activity at the surface of a ferroelectric material can be exploited to tune photoferroelectric activity.

Magnetoresistance in Hybrid Pt/CoFe2O4 Bilayers Controlled by Competing Spin Accumulation and Interfacial Chemical Reconstruction.

Pure spin currents have potential for use in energy-friendly spintronics. They can be generated by a flow of charge along a nonmagnetic metal with large spin-orbit coupling. This produces a spin accumulation at the surfaces, controllable by the magnetization of an adjacent ferromagnetic layer. Paramagnetic metals typically used are close to ferromagnetic instability and thus magnetic proximity effects can contribute to the observed angular-dependent magnetoresistance (ADMR). As interface phenomena govern the spin conductance across the metal/ferromagnetic-insulator heterostructures, unraveling these distinct contributions is pivotal for a full understanding of spin current conductance. Here, we report X-ray absorption and magnetic circular dichroism (XMCD) at Pt M and (Co, Fe) L absorption edges and atomically resolved energy electron loss spectroscopy (EELS) data of Pt/CoFe2O4 bilayers, where CoFe2O4 layers have been capped by Pt grown at different temperatures. It was found that the ADMR differs dramatically, dominated either by spin Hall magnetoresistance (SMR) associated with the spin Hall effect or by anisotropic magnetoresistance. The XMCD and EELS data indicate that the Pt layer grown at room temperature does not display any magnetic moment, whereas when grown at a higher temperature, it becomes magnetic due to interfacial Pt-(Co, Fe) alloying. These results enable differentiation of spin accumulation from interfacial chemical reconstructions and tailoring of the angular-dependent magnetoresistance.

Tailoring Lattice Strain and Ferroelectric Polarization of Epitaxial BaTiO3 Thin Films on Si(001).

Ferroelectric BaTiO3 films with large polarization have been integrated with Si(001) by pulsed laser deposition. High quality c-oriented epitaxial films are obtained in a substrate temperature range of about 300 °C wide. The deposition temperature critically affects the growth kinetics and thermodynamics balance, resulting on a high impact in the strain of the BaTiO3 polar axis, which can exceed 2% in films thicker than 100 nm. The ferroelectric polarization scales with the strain and therefore deposition temperature can be used as an efficient tool to tailor ferroelectric polarization. The developed strategy overcomes the main limitations of the conventional strain engineering methodologies based on substrate selection: it can be applied to films on specific substrates including Si(001) and perovskites, and it is not restricted to ultrathin films.