Helical magnetic state induced by chemical substitution in a polar antiferromagnet (Ni,Mn)3TeO6
일 시 : 2020년 11월 24일 화요일 16:00
연 사 : 김 재 욱 박사 (한국원자력연구원)
장 소 : 온라인 진행
초 록
Non-centrosymmetric structure give rise to various physical properties such as piezoelectricity, weak ferromagnetism, and exotic superconductivity. Recently, modulated magnetic structures, such as helical, cycloidal, or skyrmion, have been observed in various systems. Here, we report the synthesis, physical properties, and structural characterization of the antiferromagnet Ni3-xMnxTeO6 (NMTO, x < 1) with polar and chiral crystal structure. Magnetic susceptibility measurements on a single crystal shows that there exists an intermediate planar anisotropy phase that occurs between the antiferromagnetic ordering temperature (TN) at 74 K and a spin-reorientation transition at 62 K, below which the system exhibits an axial anisotropy. Both transitions are detected in dielectric and electric polarization, demonstrating a strong magnetoelectric coupling. Powder neutron diffraction experiment reveals that the intermediate phase consists of an incommensurate spin-helical state propagating along the c axis. First principle calculation shows that Mn ions chooses to occupy a specific transition-metal site. Thus, NMTO serves as a model system to study the design principle of non-collinear magnetic structure by means of chemical doping.