Condensed-Matter Physics & Materials Science Seminar

"Establishing Jeff =3/2 Ground State in a Lacunar Spinel GaTa4Se8"

Presented by Myung Joon Han, Korea Advanced Institute of Science and Technology (KAIST)

Wednesday, January 31, 2018, 1:30 pm — ISB Bldg. 734 Conf. Rm. 201 (upstairs)

In this talk, after briefly introducing the research activities in my group, I will present our recent progress on GaTa4Se8 which is known as a 'paramagnetic Mott' insulator and exhibits superconducting transition under pressure. Its low temperature behaviors found in susceptibility and specific heat measurement have not yet been clearly understood. The important first step to study these intriguing phenomena and the relationship between them is to clarify the nature of its electronic and magnetic property. By using first-principles band structure calculation and resonant inelastic x-ray scattering technique, we show that GaTa4Se8 is a novel 'Jeff=3/2 Mott' insulator in which spin-orbit interaction plays a key role to form a gap together with electronic correlation. The excitations involving the Jeff = 1/2 molecular orbital are absent only at the Ta L2 edge, manifesting the realization of the molecular Jeff = 3/2 ground state in GaTa4Se8. Based on this finding, the possible consequences of the Jeff = 3/2 state will be discussed

Hosted by: Sangkook Choi

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