Abstract: Two-dimensional (2D) magnetic materials are of current great interest for their promising applications in spintronics. Strong magnetic coupling and anisotropy are both highly desirable for achievement of a high temperature magnetic order in them . Here we first provide an example showing that a strong single ion anisotropy (SIA) makes VI3 a possible first 2D Ising ferromagnetic (FM) semiconductor , which is supported by several experiments. Then, we find that a strain could sharply tune the magnetic anisotropy in VBr3 and significantly enhance its FM order . By referring to a set of specific electronic states which could favor the Ising magnetism, we figure out FeS2 monolayer is in an unusual high valence but low-spin state, both of which yield strong FM exchange and huge SIA and then make FeS2 a high TC 2D Ising ferromagnet. Our discussion is based on the pictures of electronic structures and magnetic couplings, DFT calculations, Monte Carlo simulations, and renormalized spin-wave theory.

专家简介：吴骅教授，1994年安徽大学物理系本科毕业，1999年获中科院固体物理研究所博士学位，2000-2011年在德国马普所和德国科隆大学物理系工作，2011年起任复旦大学物理系教授。从事计算凝聚态物理和计算材料科学的研究，提出了首例二维伊辛铁磁半导体材料，预言了表面吸附原子破纪录的超强磁各向异性，阐明了氧化物电子学材料和自旋电子学材料中丰富的自旋轨道物理，并被实验证实和广泛引证。已发表论文90余篇，引用超过9400次。吴骅教授现任计算物质科学教育部重点实验室副主任、上海市物理学会计算物理专业委员会主任。曾担任复旦大学物理学系党委书记，现任复旦大学“双一流”建设办公室主任兼上海医学院学科规划与“双一流”建设办公室主任。