题目：Magnetic monopoles and quantum dynamics in spin ice materials

报告人：苏夷希  研究员

                 德国中子实验室

时间：2016年12月19日上午9点

地点：国家脉冲强磁场科学中心B206

报告摘要：

The realizations of magnetic monopoles as an emergent fractionalized quasi-particle in dipolar spin ice Ho₂Ti₂O₇ and Dy₂Ti₂O₇ pyrochlore compounds has been hailed as one of the major recent breakthroughs in condensed matter physics. Owing to the combination of a large Ising single-ion anisotropy and an effective ferromagnetic nearest-neighbor exchange interaction, the creation of magnetic monopoles as the consequence of the violation of the “2-in/2-out” ice rules becomes extremely energetically unfavorable below about 600 mK, thus leading to an almost completely suppressed spin dynamics and a frozen spin ice state possessing Pauling’s residual entropy. An intriguing question that thus arises and has already attracted tremendous amount of research efforts in the community is what may be the consequence if quantum fluctuation is invoked in the framework of the classical spin ice physics? Theories based on various forms of the quantum spin ice model have predicted the emergence of exotic ground state and collective excitations such as artificial photons. However, a convincing realization of the quantum spin ice state in real materials has not been achieved so far. In this talk, some of our recent neutron scattering studies of static and dynamics magnetic correlations in spin ice and quantum spin ice candidate materials based on frustrated pyrochlore oxides will be presented. Possible implication of our neutron scattering data within the context of the experimental signatures of magnetic monopoles and quantum dynamics will be discussed as well.

报告人简介：

Present Positions

Tenured senior scientist, Juelich Centre for Neutron Science JCNS-MLZ, Forschunszentrum Juelich, Garching, Germany

Group leader, Quantum Phenomena Group, Heinz Maier-Leibneitz Zentrum (MLZ), Garching, Germany

Academic Qualifications

PhD in condensed matter physics, Durham University, UK (in 1999)

BSc in physics, University of Science and Technology of China, China (in 1993)

Scientific Careers

Since 2012, Group leader, Quantum Phenomena Group, MLZ, Garching

Since 2005, Tenured staff member, JCNS, Forschunszentrum Juelich, Garching

2001-2004, Postdoc, Institute for Solid State Research, Forschunszentrum Juelich

2003, Visiting scientist, Advanced Photon Source, Argonne National Laboratory, USA

1999-2001, Postdoc, Hamburg Synchrotron Lab., DESY and University of Hamburg

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