The research on van der Waals (vdW) layered ferromagnets have promoted the development of nanoscale spintronics and applications. However, low-temperature ferromagnetic properties of these materials greatly hinder their applications. Here, we report pressure-enhanced ferromagnetic behaviours in layered CrSiTe3 flakes revealed by high-pressure magnetic circular dichroism (MCD) measurement. At ambient pressure, CrSiTe3 undergoes a paramagnetic-to-ferromagnetic phase transition at 32.8 K, with a negligible hysteresis loop, indicating a soft ferromagnetic behaviour. Under 4.6 GPa pressure, the soft ferromagnet changes into hard one, signalled by a rectangular hysteretic loop with remnant magnetization at zero field. Interestingly, with further increasing pressure, the coercive field (H_c) dramatically increases from 0.02 T at 4.6 GPa to 0.17 T at 7.8 GPa, and the Curie temperature (T_c^h: the temperature for closing the hysteresis loop) also increases from ~36 K at 4.6 GPa to ~138 K at 7.8 GPa. The influences of pressure on exchange interactions are further investigated by density functional theory calculations, which reveal that the in-plane nearest-neighbor exchange interaction and magneto-crystalline anisotropy increase simultaneously as pressure increases, leading to increased H_c and T_c^h in experiments. The effective interaction between magnetic couplings and external pressure offers new opportunities for both searching room-temperature layered ferromagnets and designing pressure-sensitive magnetic functional devices.
Probing defect induced room temperature ferromagnetism in CVD grown MoO3 flakes: A correlation with electronic structure and first principle-based calculations
Enhanced room temperature ferromagnetism in nanostructured MoS2 flakes by hydrogen post-treatment: Combined experimental and first-principles-based studies
2D layered transport properties from topological insulator Bi$_2$Se$_3$ single crystals and micro flakes
拓扑绝缘体如Bi $_2$ Se $_3$的低场磁输运测量对于通过对电导率的量子修正(如弱反局域化)来揭示拓扑表面态的性质是重要的。最近,各种各样的高场磁输运性能的制度,高电子密度($\sim10^{19}$ cm $^{-3}$)的报道,这可能与额外的二维层状导电性,阻碍了识别的拓扑表面状态。在这里,我们报告的量子校正的电子传导占主导地位的表面状态的半导体的情况下,这可以分析的Hikami-Larkin-Nagaoka模型的两个耦合表面的情况下,强自旋轨道相互作用。然而,在类金属的情况下,这种分析失败,需要考虑额外的二维贡献。Shubnikov-de Haas振荡和量子化霍尔电阻证明是二维层状金属行为的强有力的迹象。高品质的Bi $_2$ Se $_3$单晶剥离的宏观和微观薄片的温度依赖性的磁输运性质相结合的高分辨率透射电子显微镜和能量色散X射线光谱,确认的结构和化学计量。角分辨光电子能谱证明了在拓扑绝缘态下,晶体具有单狄拉克锥表面态和定义明确的体带隙。空间分辨的核心水平的光电子显微镜证明了表面的稳定性。
Electrically-Tunable High Curie Temperature Two-Dimensional Ferromagnetism in Van der Waals Layered Crystals
识别具有高转变温度和电可调磁性的本征低维铁磁体对于小型化自旋电子学和磁电学的发展至关重要。最近在范德华晶体CrI $_3$和Cr $_2$ Ge $_2$ Te $_6$中观察到了长程二维铁磁性,然而当减小到单层/几层时,它们的居里温度显著降低。本文利用重整化自旋波理论和第一性原理电子结构理论,对具有较高居里温度(~ 150 K)和较大带隙的van der Waals层状CrSBr和CrSeBr半导体的电调谐二维铁磁性进行了理论研究。高转变温度归因于强阴离子介导的超交换相互作用和由于大交换和单离子各向异性而引起的相当大的自旋波激发间隙。值得注意的是,空穴和电子掺杂可以将磁化易轴从面内方向切换到面外方向。这些独特的特性使单层CrSBr和CrSeBr成为实现2D自旋电子学和磁电学的有前途的平台,例如2D自旋场效应晶体管。
Ferromagnetism and orbital order in a topological ferroelectric
我们探索通过密度泛函计算的磁性掺杂的拓扑铁电体作为一种非常规的路线,多铁性。层状钙钛矿La $_{2}$ Ti $_{2}$ O $_{7}$的钒掺杂在很大程度上保持了电极化的强度并产生了稳健的铁磁有序性,因此具有适当的多铁性。掺杂剂聚集成链的显著趋势导致在一般掺杂下的绝缘特性。铁磁性源于多轨道V系统通过不寻常的“反铁”轨道顺序的对称性破缺,以及宿主的低对称性层状结构。
Above-room-temperature ferromagnetism in large-area epitaxial Fe3GaTe2/graphene van der Waals heterostructures
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V.(柏林莱布尼茨固体电子学保罗·德鲁德研究所);Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research e.V.(德累斯顿-罗森多夫亥姆霍兹中心离子束物理与材料研究所);QZabre AG(QZabre股份公司);Helmholtz Zentrum Berlin for Materialien und Energie(柏林亥姆霍兹材料与能源中心)
Observation of correlation-driven topological transport and robust ferromagnetism in 2D CrS$_2$
Institute of Physics(物理研究所);S. N. Bose National Centre for Basic Sciences(S.N. 玻色基础科学国家中心);Uppsala University(乌普萨拉大学);Montanuniversität Leoben(莱奥本矿业大学);University of Rijeka(里耶卡大学)
Nearly-room-temperature ferromagnetism and tunable anomalous Hall effect in atomically thin Fe4CoGeTe2
Renmin University of China(中国人民大学);Anhui University(安徽大学);Beijing University of Posts and Telecommunications(北京邮电大学);Korea Institute of Science and Technology (KIST)(韩国科学技术院)
Orbital Fulde-Ferrell-Larkin-Ovchinnikov state in 2H-NbS2 flakes
School of Physics, Huazhong University of Science and Technology(华中科技大学物理学院);Institute for Quantum Science and Engineering, Huazhong University of Science and Technology(华中科技大学量子科学与工程学院);Tsung-Dao Lee Institute, Shanghai Jiao Tong University(上海交通大学李政道研究所);School of Physics and Astronomy, Shanghai Jiao Tong University(上海交通大学物理与天文学院);State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences(中国科学院精密测量科学与技术创新研究院武汉物理与数学研究所国家磁共振中心磁共振与原子分子物理国家重点实验室)
Intrinsic magnetic topological insulators in van der Waals layered MnBi$_2$Te$_4$-family materials
磁性与拓扑学的相互作用是凝聚态物理和材料科学的重要研究课题,它为探索量子反常霍尔效应、轴子电动力学和马约拉纳费米子等新兴物理提供了巨大的机会。然而,由于缺乏合适的工作材料,这些奇异的物理效应在实验中很少实现。在这里,我们预测,范德华层状MnBi $_2$ Te $_4$ -家庭材料显示二维(2D)铁磁性在单层和三维(3D)$A$型反铁磁性在块体,这可以作为一个新一代的材料平台,为国家的最先进的研究。值得注意的是,我们预测非常丰富的拓扑量子效应与突出的功能,在实验可用的材料MnBi $_2$ Te $_4$,包括3D反铁磁拓扑绝缘体与长期寻求的拓扑轴子状态,II型磁性Weyl半金属(WSM)与简单的一对Weyl点,和高温本征QAH效应。这些惊人的预测,如果实验证明,可能会深刻地改变拓扑量子物理学的未来研究和技术。
High temperature ferromagnetism in epitaxial monolayers of Co-doped Fe5GeTe2
University Grenoble Alpes(格勒诺布尔阿尔卑斯大学);CNRS(法国国家科学研究中心);CEA(法国原子能和替代能源委员会);IRIG-Spintec(IRIG自旋技术中心);European Synchrotron Radiation Facility(欧洲同步辐射装置);IRIG-MEM(IRIG分子与材料物理研究所);Synchrotron SOLEIL(SOLEIL同步辐射中心);Institut Universitaire de France (IUF)(法兰西学院)
Tunable magnetism in 2D organic-ion-intercalated MnPS3 via molecule-dependent vacancy generation
CIC nanoGUNE(CIC纳米技术研究中心);Department of Photonics, Izmir Institute of Technology(伊兹密尔理工大学光子学系);Dept. of Inorganic Chemistry, University of Chemistry and Technology Prague(布拉格化学与技术大学无机化学系);ALBA Synchrotron Light Source(阿尔巴同步辐射光源);Centro de Física de Materiales (CSIC-UPV-EHU) and Materials Physics Center (MPC)(材料物理中心(西班牙国家研究委员会-巴斯克国立大学)和材料物理中心);Donostia International Physics Center (DIPC)(圣塞巴斯蒂安国际物理中心);IKERBASQUE, Basque Foundation for Science(伊克尔巴斯基克,巴斯克科学基金会)