Intertwined Magnetic and Nematic Orders in Semiconducting KFe0.8Ag1.2Te2

by Prof. Jie Ma (University of California, Berkeley)

Wednesday 5 Jun 2019, 13:30 → 16:50 Asia/Shanghai

TDLI Meeting Room 200

Abstract

Strongly correlated materials often adopt electronic ground states that break rotational-symmetry of their underlying crystal structures, analogous to nematic liquid crystals. Such states are found in close proximity to and are an essential aspect of iron-based superconductors. Important questions in these materials concern the nature of their nematic and magnetic orders, whether the magnetism is due to local moments or itinerant electrons, and whether the nematic order is driven by the magnetic or the orbital degree of freedom. Using scattering techniques we demonstrate the presence of intertwined nematic and stripe-type magnetic orders insemiconducting KFe_0.8Ag_1.2Te₂, a structural analogue of iron-based superconductors. A small strain induces sizeable magnetic anisotropy above the magnetic and nematic transition temperatures, indicating a largenematic susceptibility while realizing a strain-induced spin-nematic state. Because KFe_0.8Ag_1.2Te₂ is a semiconductor devoid of a Fermi surface, its magnetic and nematic orders likely arise from interactions between local moments. Such interactions should be important for systems containing Fe-pnitogen/chalcogen planes in general, including iron-based superconductors. Our results suggest several aspects of the phenomenology of iron-based superconductor result from the unique geometry of the iron-pnictogen/chalcogen planes.

Biography

Research Experience

2017–present  Postdoctoral Scholar, University of California, Berkeley.

2017–2017      RCQM/Smalley-Curl Postdoctoral Fellow in Quantum Materials, Rice University, Houston.

2011–2013      Research Assistant, Univeristy of Tennessee, Knoxville.

Education

2013–2017  PhD, Rice University, Houston.  Advisor: Pengcheng Dai

2010–2013  PhD candidate, University of Tennessee, Knoxville.  Advisor: Pengcheng Dai

2006–2010  Bachelor of Science, Zhejiang University, Hangzhou

Research Interest

Using scattering techniques to probe the physics of quantum materials, such as unconventional superconductors and low-dimensional magnets

Synthesis and characterization of novel materials

Division

Condensed Matter