School of Physical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India

So far, magnetic materials with collinear spin alignments have dominated the field of spintronics. It was recently proposed that the back and forth motion of an atomically engineered chiral domain wall can provide a basis for novel high density solid-state storage memory devices - Racetrack  Memories [Science 320, 190 (2008)]. However, the threshold current to move such non-collinear domain walls is much higher than that expected theoretically. In contrast, much lower threshold currents have been found for the motion of recently discovered skyrmions, which are topologically stable vortex-like objects with a twisted spin configuration [Nature 465, 901 (2010)]. Magnetic materials with broken inversion symmetry, where the asymmetric Dzyaloshinskii–Moriya interaction modifies the uniform magnetic state to a swirling state, are considered to be suitable candidates to achieve skyrmions. In this direction, the tetragonal Heusler compounds with D2d crystal symmetry are potential candidates for realizing antiskyrmions. This has been demonstrated in the recent work that show existence of antiskyrmion lattice over a wide temperature interval up to 400 K in Mn-Pt-Sn based Heusler materials [Nature 548, 561 (2017)]. I will also present some of the very recent results where we found a large topological Hall effect in some new Heusler materials and some potential candidates for antiferromagnetic antiskyrmions.

报告人：Dr. Ajaya K. Nayak is a leading scientist in the field of Magnetism. Dr. Nayak received his Ph.D. in Condensed Matter Physics from Indian Institute of Technology Bombay (IIT Bombay), Mumbai, India in 2011.  He received the best Ph.D. thesis award for his excellent work in magnetic shape memory alloys. Afterward, Dr. Nayak moved to Germany to pursue post doctoral research in Max Planck Institute for Chemical Physics of Solids, Dresden and Max Planck Institute of Microstructure Physics, Halle. He moved back to India in December 2016 to join as an Assistant Professor in National Institute of Science Education and Research (NISER), Bhubaneswar, India. His current research is mainly focused on non-collinear magnetic structures, such as, skyrmions/antiskyrmions. His research mostly utilizes Lorentz TEM, topological/anomalous Hall effect measurements using PPMS and high magnetic fields up to 60 T for magnetic and transport measurements. He has published about 45 research articles in many high impact journals, such as, Nature, Nature Materials, Nature Physics, Science advances, Advanced Materials, Physical Review Letters, etc.

报告邀请人：李子安 (82648001, zali79@iphy.ac.cn)，先进材料与结构分析实验室A06组