ABSTRACT
Introducción Las fracturas del tercio distal de tibia son en su mayoría consecuencia de un traumatismo de alta energía con importante afectación de partes blandas siendo mas frecuentes en varones. Este tipo de fracturas se diferencian de la fractura articular de pilón tibial en su mecanismo de lesión, manejo y pronóstico. El objetivo del presente estudio fue analizar y comparar los resultados obtenidos en el tratamiento de las fracturas de tercio distal de tibia sin extensión articular mediante placa bloqueada y clavo intramedular. Material y métodos: Realizamos un estudio retrospectivo en el que se incluyeron todos los pacientes con diagnostico «fractura de tercio distal de tibia» segmento 43A según la clasificación propuesta por «Trauma Orthopedic Association» intervenidos entre enero del 2015 y mayo del 2019. Obtuvimos 24 pacientes intervenidos mediante clavo intramedular y 29 mediante placa bloqueada. Resultados: La muestra incluyó 53 pacientes (36 varones y 17 mujeres) con una media de edad de 51 años (rango: 15-77 años). El tiempo de seguimiento medio fue de 6 meses (3-30 meses). No se hallaron diferencias significativas en el tiempo de consolidación de la fractura, aunque el inicio de la deambulación con carga fue mas temprano en el grupo clavo. Discusión: En la actualidad no existe consenso acerca del manejo terapeútico de las fracturas distales de tibia sin extensión articular. Conclusiones: Dados los resultados obtenidos consideramos que tanto la osteosíntesis con clavo intramedular como con placa bloqueada son opciones válidas en el tratamiento de las fracturas del tercio distal de tibia.(AU)
Introduction: Fractures of the distal third of the tibia are mostly the consequence of high-energy trauma with significant soft tissue involvement, being more frequent in men.These types of fractures differ from the tibial pilon joint fracture in their mechanism of injury, management and prognosis. The objective of the present study was to analyze and compare the results obtained in the treatment of fractures of the distal third of the tibia without joint extension using a locked plate and intramedullary nail. Material and methods: We carried out a retrospective study with patients diagnosed of distal third tibia fracture segment 43A according to the classification proposed by the Trauma Orthopedic Association who were intervened between January 2015 and May 2019 were included. We obtained 24 patients intervened with a nail intramedullary and 29 using a blocked plate. Results: The study included 53 patients, 36 men and 17 women with a mean age of 51 years (range: 15-77 years). The mean follow-up time was 6 months (330 months). No significant differences were found in the time to fracture healing, although the beginning with load walking was earlier in the nail group. Discussion: Currently there is no consensus on the therapeutic management of distal tibia fractures without joint extension. Conclusions: After analyzing the results, we consider that both intramedullary nail osteosynthesis and a locked plate are valid options in the treatment of fractures of the distal third of the tibia.(AU)
Subject(s)
Humans , Male , Female , Adolescent , Young Adult , Adult , Middle Aged , Aged , Tibia/injuries , Tibia/surgery , Tibial Fractures/surgery , Tibial Fractures/diagnostic imaging , Bone Nails , Wounds and Injuries , Fractures, Bone/drug therapy , Fractures, Bone/therapy , Orthopedics , Traumatology , Retrospective StudiesABSTRACT
Introduction: Fractures of the distal third of the tibia are mostly the consequence of high-energy trauma with significant soft tissue involvement, being more frequent in men.These types of fractures differ from the tibial pilon joint fracture in their mechanism of injury, management and prognosis. The objective of the present study was to analyze and compare the results obtained in the treatment of fractures of the distal third of the tibia without joint extension using a locked plate and intramedullary nail. Material and methods: We carried out a retrospective study with patients diagnosed of distal third tibia fracture segment 43A according to the classification proposed by the Trauma Orthopedic Association who were intervened between January 2015 and May 2019 were included. We obtained 24 patients intervened with a nail intramedullary and 29 using a blocked plate. Results: The study included 53 patients, 36 men and 17 women with a mean age of 51 years (range: 15-77 years). The mean follow-up time was 6 months (330 months). No significant differences were found in the time to fracture healing, although the beginning with load walking was earlier in the nail group. Discussion: Currently there is no consensus on the therapeutic management of distal tibia fractures without joint extension. Conclusions: After analyzing the results, we consider that both intramedullary nail osteosynthesis and a locked plate are valid options in the treatment of fractures of the distal third of the tibia.(AU)
Introducción Las fracturas del tercio distal de tibia son en su mayoría consecuencia de un traumatismo de alta energía con importante afectación de partes blandas siendo mas frecuentes en varones. Este tipo de fracturas se diferencian de la fractura articular de pilón tibial en su mecanismo de lesión, manejo y pronóstico. El objetivo del presente estudio fue analizar y comparar los resultados obtenidos en el tratamiento de las fracturas de tercio distal de tibia sin extensión articular mediante placa bloqueada y clavo intramedular. Material y métodos: Realizamos un estudio retrospectivo en el que se incluyeron todos los pacientes con diagnostico «fractura de tercio distal de tibia» segmento 43A según la clasificación propuesta por «Trauma Orthopedic Association» intervenidos entre enero del 2015 y mayo del 2019. Obtuvimos 24 pacientes intervenidos mediante clavo intramedular y 29 mediante placa bloqueada. Resultados: La muestra incluyó 53 pacientes (36 varones y 17 mujeres) con una media de edad de 51 años (rango: 15-77 años). El tiempo de seguimiento medio fue de 6 meses (3-30 meses). No se hallaron diferencias significativas en el tiempo de consolidación de la fractura, aunque el inicio de la deambulación con carga fue mas temprano en el grupo clavo. Discusión: En la actualidad no existe consenso acerca del manejo terapeútico de las fracturas distales de tibia sin extensión articular. Conclusiones: Dados los resultados obtenidos consideramos que tanto la osteosíntesis con clavo intramedular como con placa bloqueada son opciones válidas en el tratamiento de las fracturas del tercio distal de tibia.(AU)
Subject(s)
Humans , Male , Female , Adolescent , Young Adult , Adult , Middle Aged , Aged , Tibia/injuries , Tibia/surgery , Tibial Fractures/surgery , Tibial Fractures/diagnostic imaging , Bone Nails , Wounds and Injuries , Fractures, Bone/drug therapy , Fractures, Bone/therapy , Orthopedics , Traumatology , Retrospective StudiesABSTRACT
INTRODUCTION: Fractures of the distal third of the tibia are mostly the consequence of high-energy trauma with significant soft tissue involvement, being more frequent in men. These types of fractures differ from the tibial pilon joint fracture in their mechanism of injury, management and prognosis. The objective of the present study was to analyze and compare the results obtained in the treatment of fractures of the distal third of the tibia without joint extension using a locked plate and intramedullary nail. MATERIAL AND METHODS: We carried out a retrospective study with patients diagnosed of "distal third tibia fracture" segment 43A according to the classification proposed by the "Trauma Orthopedic Association" who were intervened between January 2015 and May 2019 were included. We obtained 24 patients intervened with a nail intramedullary and 29 using a blocked plate. RESULTS: The study included 53 patients, 36 men and 17 women with a mean age of 51 years (range: 15-77 years). The mean follow-up time was 6 months (3-30 months). No significant differences were found in the time to fracture healing, although the beginning with load walking was earlier in the nail group. DISCUSSION: Currently there is no consensus on the therapeutic management of distal tibia fractures without joint extension. CONCLUSIONS: After analyzing the results, we consider that both intramedullary nail osteosynthesis and a locked plate are valid options in the treatment of fractures of the distal third of the tibia.
ABSTRACT
OBJECTIVE: To evaluate the results of surgical treatment of intraarticular calcaneal fractures, and also to analyze the variables that influence the final clinical and radiological outcomes as well as the complications. MATERIAL AND METHODS: We retrospectively analyzed 86 intraarticular calcaneal fractures in 78 patients, who underwent surgery with an extended lateral approach and reconstruction plate. The mean age was 48 years (16-74 years) and the mean follow-up was 4.6 years (9-99 months); 54 patients (69.2%) suffered falls from less than 3m in height or banal injuries and 24 patients (30.8%) falls from more than 3m in height or high energy-accidents. According to the Sanders classification we operated 12 (15%) typeII, 54 (62.8%) typeIII and 20 (23.2%) typeIV fractures. RESULTS: The postoperative mean AOFAS score was 73.9 points, with good or excellent results in 57% of the patients. Twelve cases (14%) suffered surgical wound complications and 11 (12.8%) required subtalar arthrodesis. Significantly better results were obtained in the patients younger than 30 years old, patients that fell from less than 3m in height and patients with Sanders fractures types II and III compared to typeIV, which were associated with higher rate of subtalar arthrodesis. CONCLUSIONS: We consider that open reduction and internal fixation of intraarticular fractures of the calcaneus with reconstruction plate is a valid treatment alternative. Given the complications described and the secondary subtalar arthrodesis rate, we recommend a meticulous technique carried out by experienced surgeons.
ABSTRACT
The ability to control a magnetic phase with an electric field is of great current interest for a variety of low power electronics in which the magnetic state is used either for information storage or logic operations. Over the past several years, there has been a considerable amount of research on pathways to control the direction of magnetization with an electric field. More recently, an alternative pathway involving the change of the magnetic state (ferromagnet to antiferromagnet) has been proposed. In this paper, we demonstrate electric field control of the Anomalous Hall Transport in a metamagnetic FeRh thin film, accompanying an antiferromagnet (AFM) to ferromagnet (FM) phase transition. This approach provides us with a pathway to "hide" or "reveal" a given ferromagnetic region at zero magnetic field. By converting the AFM phase into the FM phase, the stray field, and hence sensitivity to external fields, is decreased or eliminated. Using detailed structural analyses of FeRh films of varying crystalline quality and chemical order, we relate the direct nanoscale origins of this memory effect to site disorder as well as variations of the net magnetic anisotropy of FM nuclei. Our work opens pathways toward a new generation of antiferromagnetic - ferromagnetic interactions for spintronics.
ABSTRACT
We report here the O K-edge x-ray absorption spectra of hexagonal and orthorhombic YMnO3 thin films, aiming at comparing the changes in the Mn 3d bands as well as the role of Y 4d-O 2p hybridization. The experimental results were analyzed using first principles (GGA) band structure calculations. The spectra present clear differences in the Mn 3d bands, which are attributed to changes in the Mn-O coordination and symmetry. A strong Y 4d-O 2p hybridization is observed in both the hexagonal and orthorhombic films, and its possible role on the occurrence of the observed ferroelectricity is discussed.
ABSTRACT
Antiferromagnets offer a unique combination of properties including the radiation and magnetic field hardness, the absence of stray magnetic fields, and the spin-dynamics frequency scale in terahertz. Recent experiments have demonstrated that relativistic spin-orbit torques can provide the means for an efficient electric control of antiferromagnetic moments. Here we show that elementary-shape memory cells fabricated from a single-layer antiferromagnet CuMnAs deposited on a III-V or Si substrate have deterministic multi-level switching characteristics. They allow for counting and recording thousands of input pulses and responding to pulses of lengths downscaled to hundreds of picoseconds. To demonstrate the compatibility with common microelectronic circuitry, we implemented the antiferromagnetic bit cell in a standard printed circuit board managed and powered at ambient conditions by a computer via a USB interface. Our results open a path towards specialized embedded memory-logic applications and ultra-fast components based on antiferromagnets.
ABSTRACT
Antiferromagnetic spintronics is an emerging field; antiferromagnets can improve the functionalities of ferromagnets with higher response times, and having the information shielded against external magnetic field. Moreover, a large list of aniferromagnetic semiconductors and metals with Néel temperatures above room temperature exists. In the present manuscript, we persevere in the quest for the limits of how large can anisotropic magnetoresistance be in antiferromagnetic materials with very large spin-orbit coupling. We selected IrMn as a prime example of first-class moment (Mn) and spin-orbit (Ir) combination. Isothermal magnetotransport measurements in an antiferromagnetic-metal(IrMn)/ferromagnetic-insulator thin film bilayer have been performed. The metal/insulator structure with magnetic coupling between both layers allows the measurement of the modulation of the transport properties exclusively in the antiferromagnetic layer. Anisotropic magnetoresistance as large as 0.15% has been found, which is much larger than that for a bare IrMn layer. Interestingly, it has been observed that anisotropic magnetoresistance is strongly influenced by the field cooling conditions, signaling the dependence of the found response on the formation of domains at the magnetic ordering temperature.
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Commercial magnetic memories rely on the bistability of ordered spins in ferromagnetic materials. Recently, experimental bistable memories have been realized using fully compensated antiferromagnetic metals. Here we demonstrate a multiple-stable memory device in epitaxial MnTe, an antiferromagnetic counterpart of common II-VI semiconductors. Favourable micromagnetic characteristics of MnTe allow us to demonstrate a smoothly varying zero-field antiferromagnetic anisotropic magnetoresistance (AMR) with a harmonic angular dependence on the writing magnetic field angle, analogous to ferromagnets. The continuously varying AMR provides means for the electrical read-out of multiple-stable antiferromagnetic memory states, which we set by heat-assisted magneto-recording and by changing the writing field direction. The multiple stability in our memory is ascribed to different distributions of domains with the Néel vector aligned along one of the three magnetic easy axes. The robustness against strong magnetic field perturbations combined with the multiple stability of the magnetic memory states are unique properties of antiferromagnets.
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Antiferromagnetic materials are internally magnetic, but the direction of their ordered microscopic moments alternates between individual atomic sites. The resulting zero net magnetic moment makes magnetism in antiferromagnets externally invisible. This implies that information stored in antiferromagnetic moments would be invisible to common magnetic probes, insensitive to disturbing magnetic fields, and the antiferromagnetic element would not magnetically affect its neighbours, regardless of how densely the elements are arranged in the device. The intrinsic high frequencies of antiferromagnetic dynamics represent another property that makes antiferromagnets distinct from ferromagnets. Among the outstanding questions is how to manipulate and detect the magnetic state of an antiferromagnet efficiently. In this Review we focus on recent works that have addressed this question. The field of antiferromagnetic spintronics can also be viewed from the general perspectives of spin transport, magnetic textures and dynamics, and materials research. We briefly mention this broader context, together with an outlook of future research and applications of antiferromagnetic spintronics.
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Recent studies in devices comprising metal antiferromagnets have demonstrated the feasibility of a novel spintronic concept in which spin-dependent phenomena are governed by an antiferromagnet instead of a ferromagnet. Here we report experimental observation of the anisotropic magnetoresistance in an antiferromagnetic semiconductor Sr2IrO4. Based on ab initio calculations, we associate the origin of the phenomenon with large anisotropies in the relativistic electronic structure. The antiferromagnet film is exchange coupled to a ferromagnet, which allows us to reorient the antiferromagnet spin-axis in applied magnetic fields via the exchange spring effect. We demonstrate that the semiconducting nature of our AFM electrode allows us to perform anisotropic magnetoresistance measurements in the current-perpendicular-to-plane geometry without introducing a tunnel barrier into the stack. Temperature-dependent measurements of the resistance and anisotropic magnetoresistance highlight the large, entangled tunabilities of the ordinary charge and spin-dependent transport in a spintronic device utilizing the antiferromagnet semiconductor.
ABSTRACT
The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets.
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We report on a systematic study of the stress transferred from an electromechanical piezo-stack into GaAs wafers under a wide variety of experimental conditions. We show that the strains in the semiconductor lattice, which were monitored in situ by means of X-ray diffraction, are strongly dependent on both the wafer thickness and on the selection of the glue which is used to bond the wafer to the piezoelectric actuator. We have identified an optimal set of parameters that reproducibly transfers the largest distortions at room temperature. We have studied strains produced not only by the frequently used uniaxial piezostressors but also by the biaxial ones which replicate the routinely performed experiments using substrate-induced strains but with the advantage of a continuously tunable lattice distortion. The time evolution of the strain response and the sample tilting and/or bending are also analyzed and discussed.
ABSTRACT
Recent studies have demonstrated the potential of antiferromagnets as the active component in spintronic devices. This is in contrast to their current passive role as pinning layers in hard disk read heads and magnetic memories. Here we report the epitaxial growth of a new high-temperature antiferromagnetic material, tetragonal CuMnAs, which exhibits excellent crystal quality, chemical order and compatibility with existing semiconductor technologies. We demonstrate its growth on the III-V semiconductors GaAs and GaP, and show that the structure is also lattice matched to Si. Neutron diffraction shows collinear antiferromagnetic order with a high Néel temperature. Combined with our demonstration of room-temperature-exchange coupling in a CuMnAs/Fe bilayer, we conclude that tetragonal CuMnAs films are suitable candidate materials for antiferromagnetic spintronics.
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Ferroelectric (FE) and ferromagnetic (FM) materials engineered in horizontal heterostructures allow interface-mediated magnetoelectric coupling. The so-called converse magnetoelectric effect (CME) has been already demonstrated by electric-field poling of the ferroelectric layers and subsequent modification of the magnetic state of adjacent ferromagnetic layers by strain effects and/or free-carrier density tuning. Here we focus on the direct magnetoelectric effect (DME) where the dielectric state of a ferroelectric thin film is modified by a magnetic field. Ferroelectric BaTiO3 (BTO) and ferromagnetic CoFe2O4 (CFO) oxide thin films have been used to create epitaxial FE/FM and FM/FE heterostructures on SrTiO3(001) substrates buffered with metallic SrRuO3. It will be shown that large ferroelectric polarization and DME can be obtained by appropriate selection of the stacking order of the FE and FM films and their relative thicknesses. The dielectric permittivity, at the structural transitions of BTO, is strongly modified (up to 36%) when measurements are performed under a magnetic field. Due to the insulating nature of the ferromagnetic layer and the concomitant absence of the electric-field effect, the observed DME effect solely results from the magnetostrictive response of CFO elastically coupled to the BTO layer. These findings show that appropriate architecture and materials selection allow overcoming substrate-induced clamping in multiferroic multi-layered films.
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We employ antiferromagnetic tunneling anisotropic magnetoresistance to study the behavior of antiferromagnetically ordered moments in IrMn exchange coupled to NiFe. Experiments performed by common laboratory tools for magnetization and electrical transport measurements allow us to directly link the broadening of the NiFe hysteresis loop and its shift (exchange bias) to the rotation and pinning of antiferromagnetic moments in IrMn. At higher temperatures, the broadened loops show zero shift, which correlates with the observation of fully rotating antiferromagnetic moments inside the IrMn film. The onset of exchange bias at lower temperatures is linked to a partial rotation between distinct metastable states and pinning of the IrMn antiferromagnetic moments in these states. The observation complements common pictures of exchange bias and reveals an electrically measurable memory effect in an antiferromagnet.
ABSTRACT
A spin valve is a microelectronic device in which high- and low-resistance states are realized by using both the charge and spin of carriers. Spin-valve structures used in modern hard-drive read heads and magnetic random access memoriescomprise two ferromagnetic electrodes whose relative magnetization orientations can be switched between parallel and antiparallel configurations, yielding the desired giant or tunnelling magnetoresistance effect. Here we demonstrate more than 100% spin-valve-like signal in a NiFe/IrMn/MgO/Pt stack with an antiferromagnet on one side and a non-magnetic metal on the other side of the tunnel barrier. Ferromagneticmoments in NiFe are reversed by external fields of approximately 50 mT or less, and the exchange-spring effect of NiFe on IrMn induces rotation of antiferromagnetic moments in IrMn, which is detected by the measured tunnelling anisotropic magnetoresistance. Our work demonstrates a spintronic element whose transport characteristics are governed by an antiferromagnet. It demonstrates that sensitivity to low magnetic fields can be combined with large, spin-orbit-coupling-induced magnetotransport anisotropy using a single magnetic electrode. The antiferromagnetic tunnelling anisotropic magnetoresistance provides a means to study magnetic characteristics of antiferromagnetic films by an electronic-transport measurement.
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We demonstrate that the magnetization of a ferromagnet in contact with an antiferromagnetic multiferroic (LuMnO(3)) can be speedily reversed by electric-field pulsing, and the sign of the magnetic exchange bias can switch and recover isothermally. As LuMnO(3) is not ferroelastic, our data conclusively show that this switching is not mediated by strain effects but is a unique electric-field driven decoupling of the ferroelectric and antiferromagnetic domain walls. Their distinct dynamics are essential for the observed magnetic switching.
ABSTRACT
Polarized infrared reflectivity was measured between 5 and 300 K on a 17 nm thick, 1.1% compressively strained epitaxial (001) SrTiO(3) film and the orthorhombic (110) NdGaO(3) substrate upon which it was grown. A strong in-plane infrared anisotropy of the NdGaO(3) substrate was observed and polar modes with B(1u)-and a mixture of B(2u) + B(3u)-symmetry were seen. At low temperatures three new modes arose in the 90-130 cm( - 1) range, which we assigned to 4f Nd electronic transitions. The in-plane SrTiO(3) film phonons showed strong stiffening compared to the phonon frequencies of bulk unstrained SrTiO(3), particularly the soft mode, and the in-plane phonon peaks were found to split. No anomalies were detected as a function of temperature in either the infrared response or lattice parameters of the compressively strained SrTiO(3) film, providing an absence of evidence for the out-of-plane ferroelectric phase transition predicted by theory.
ABSTRACT
Cycloidal magnetic order occurring in some AMnO(3) perovskites is known to induce ferroelectricity. The polarization is perpendicular to the propagation vector direction of the cycloid and its chirality, and therefore it is directly related to the chiral domain structure. We show that the switching process of chiral domains is sensitively dependent on the magnetoelectric history of the sample. Moreover, by appropriate field cycling, magnetic order can display partial chiral memory. We argue that memory results from electric field coupling of cycloidal domain and nucleation and pinning of chiral domain walls, much like the domain structure in other ferroic systems.
