Current-driven writing process in antiferromagnetic Mn2Au for memory applications.

Current pulse driven Néel vector rotation in metallic antiferromagnets is one of the most promising concepts in antiferromagnetic spintronics. We show microscopically that the Néel vector of epitaxial thin films of the prototypical compound Mn2Au can be reoriented reversibly in the complete area of cross shaped device structures using single current pulses. The resulting domain pattern with aligned staggered magnetization is long term stable enabling memory applications. We achieve this switching with low heating of ≈20 K, which is promising regarding fast and efficient devices without the need for thermal activation. Current polarity dependent reversible domain wall motion demonstrates a Néel spin-orbit torque acting on the domain walls.

Readout of an antiferromagnetic spintronics system by strong exchange coupling of Mn2Au and Permalloy.

In antiferromagnetic spintronics, the read-out of the staggered magnetization or Néel vector is the key obstacle to harnessing the ultra-fast dynamics and stability of antiferromagnets for novel devices. Here, we demonstrate strong exchange coupling of Mn2Au, a unique metallic antiferromagnet that exhibits Néel spin-orbit torques, with thin ferromagnetic Permalloy layers. This allows us to benefit from the well-established read-out methods of ferromagnets, while the essential advantages of antiferromagnetic spintronics are only slightly diminished. We show one-to-one imprinting of the antiferromagnetic on the ferromagnetic domain pattern. Conversely, alignment of the Permalloy magnetization reorients the Mn2Au Néel vector, an effect, which can be restricted to large magnetic fields by tuning the ferromagnetic layer thickness. To understand the origin of the strong coupling, we carry out high resolution electron microscopy imaging and we find that our growth yields an interface with a well-defined morphology that leads to the strong exchange coupling.

[Clinicopathological analysis of lung metastatic tumor].

Objective: To investigate the clinicopathological features and differential diagnosis of metastatic tumors in the lung. Methods: The clinicopathological data of 226 metastatic tumors in the lung were collected at Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, from January 2014 to December 2018, and the pathomorphological characteristics were analyzed. Results: There were 84 males and 142 females, with an age range from 13 to 77 years. There were 122 patients with multiple pulmonary nodules and 104 patients with solitary pulmonary nodule. The tumors of the highest frequencies were colorectal cancer (n=59), followed by trophoblast tumor (n=44), kidney cancer (n=31), breast cancer (n=20), cervix cancer (n=14), and urinary urothelium cancer (n=8). The time from the diagnosis of primary tumors to metastasis and the status of surgical treatment varied by tumor origin. The morphology of metastatic lung tumors overlapped with that of the primary tumors to some extent. The relative specific morphological characteristics and the presence of carcinoma in situ surrounding the tumors should be carefully searched for to confirm the tumor origin. The metastatic tumors of the lung had morphological characteristics, immunohistochemical TTF1 (-) and tumor of various sources, while the primary tumor differentiation had relatively specific antibodies: colorectal cancer CK20 (+), CDX2 (+), CK7 (-); malignant trophoblastic tumor, HCG (+); renal clear cell carcinoma CD10 (+), vimentin (+), CK7 (-); breast cancer, GATA3 and ER (+); cervical cancer, p16 (+); urothelial carcinoma, CK20, p63 and GATA3 (+). Conclusions: There is overlap between pulmonary metastatic tumor and primary tumor in morphology. Therefore, the diagnosis should be made by combining clinical history, pathological morphology and immunophenotypic characteristics.

[Clinicopathological features and prognosis of synchronous bilateral breast cancers].

Objective: To study the clinicopathologic characteristics and relevant factors affecting prognosis of patients with synchronous bilateral breast cancer. Methods: The clinical data, pathologic characteristics and immunohistochemical expression characteristics of 151 patients with synchronous bilateral breast cancers diagnosed in Peking Union Medical College Hospital from 2008 to 2018 were collected and analyzed. The factors affecting the prognosis were analyzed by Log rank test, Kaplan-Meier survival analysis, Cox regression and other methods. Results: Synchronous bilateral breast cancer cases accounted for 1.2% (151/12 239) of all breast cancer patients in the same period, and 14.6% (22/151) had a family history. The patients' age range was 22-88 years, mainly female, with a mean survival of 42.5 months. There were 106 patients with synchronous bilateral invasive breast cancers, 6 patients with synchronous bilateral breast cancer in situ, and 39 patients with unilateral invasive breast cancer and unilateral breast cancer in situ. In synchronous bilateral invasive breast cancers, the histological type was mainly non-specific type (84.9%, 180/212), the histological grade was mainly Grade 2 (60.8%,129/212), the TNM stage was mainly stage Ⅰ (50.5%, 107/212), the tumor size was mainly T1 (68.9%, 146/212), and the regional lymph node was mainly N0 (61.8%, 131/212). The molecular subtypes were mainly Luminal A-like (38.1%, 75/197) and Luminal B-like (43.7%, 86/197); ER (78.2%, 154/197) and PR (72.1%,142/197)were mainly positive, and HER2 was mainly negative (91.9%, 181/197). There were 85 (80.2%) patients and 75 (70.8%) patients with the same histological type and histological grade on both sides, respectively. The concordance of tumor size T stage and the regional lymph nodes N stage were 58.5% (62/106) and 55.7% (59/106), respectively. The concordance of molecular subtype was 54.9% (50/91), and the concordance of ER, PR, HER2 and Ki-67 were 83.5% (76/91), 76.9% (70/91), 89.0% (81/91) and 59.3% (54/91), respectively. The expression of ER and PR in synchronous bilateral invasive breast cancer was significantly correlated with prognosis (P<0.05). Conclusions: Among patients with synchronous bilateral breast cancers, bilateral invasive breast cancer is the most common, the prognosis is the worst, and the pathologic characteristics of bilateral breast cancer tend to be consistent. The expression of ER and PR in synchronous bilateral invasive breast cancer is significantly correlated with prognosis, that is, best for bilateral ER-positive patients, worst for bilateral ER-negative patients, and intermediate for unilateral ER-positive patients, thus suggesting the importance of ER and PR detection in synchronous bilateral invasive breast cancers.

Surface Phase Metastability during Langmuir Evaporation.

We have directly imaged the spontaneous formation of metastable surface phase domains on GaAs(001) during Langmuir evaporation. Eventually, these metastable phases transform to the thermodynamically stable parent phase, producing a dynamic phase coexistence with a temperature dependent, time-averaged coverage. Monte Carlo simulations are used to identify the key kinetic processes and investigate the interplay between phase metastability and evolving surface morphology. This is used to explain the measured temperature dependence of the time-averaged coverage.

Selected energy dark-field imaging using low energy electrons for optimal surface phase discrimination.

We propose a general strategy for surface phase discrimination by dark-field imaging using low energy electrons, which maximizes contrast using diffraction spots, at selected optimal energies. The method can be automated to produce composite phase maps in real space and study the dynamics of complex phase transformations in real-time. To illustrate the capabilities of the technique, surface phases are mapped in the vicinity of liquid Ga droplets on the technologically important GaAs (001) surface.

Observation of Weakened V-V Dimers in the Monoclinic Metallic Phase of Strained VO_{2}.

Emergent order at mesoscopic length scales in condensed matter can provide fundamental insight into the underlying competing interactions and their relationship with the order parameter. Using spectromicroscopy, we show that mesoscopic stripe order near the metal-insulator transition (MIT) of strained VO_{2} represents periodic modulations in both crystal symmetry and V-V dimerization. Above the MIT, we unexpectedly find the long-range order of V-V dimer strength and crystal symmetry become dissociated beyond ≈200 nm, whereas the conductivity transition proceeds homogeneously in a narrow temperature range.

Metal-dielectric transition in Sn-intercalated graphene on SiC(0001).

The Sn intercalation into a buffer layer graphene grown on 4H-SiC(0001) substrate has been studied with spectroscopic photoemission and low energy electron microscope. Both SnSix and SnOx interfacial layers are found to form below the buffer layer, converting it into a quasi-free-standing monolayer graphene. Combining the various operation modes of the microscope allows a detailed insight into the formation processes of the interlayers and their thermal stability. In particular, at the interface we observed a reversible transition from silicide to oxide after exposure to ambient pressure and subsequent annealing. This metal-dielectric transition might be useful for interface engineering in graphene-based devices.

Direct observation of decoupled structural and electronic transitions and an ambient pressure monocliniclike metallic phase of VO2.

We report the simultaneous measurement of the structural and electronic components of the metal-insulator transition (MIT) of VO2 using electron and photoelectron spectroscopies and microscopies. We show that these evolve over different temperature scales, and are separated by an unusual monocliniclike metallic phase. Our results provide conclusive evidence that the new monocliniclike metallic phase, recently identified in high-pressure and nonequilibrium measurements, is accessible in the thermodynamic transition at ambient pressure, and we discuss the implications of these observations on the nature of the MIT in VO2.