JOURNAL CLUB DO DEPARTAMENTO DE FÍSICA DOS MATERIAIS E MECÂNICA
Nesta semana o Prof. Fernando Assis Garcia, do Departamento de Física Aplicada, apresentará o artigo: “Continuous Excitations of the Triangular-Lattice Quantum Spin Liquid YbMgGaO4” Joseph A. M. Paddison, Marcus Daum, Zhiling Dun, Georg Ehlers, Yaohua Liu, Matthew B. Stone, Haidong Zhou & Martin Mourigal , Nature Physics 13, 117–122 (2017) doi:10.1038/nphys3971
Dia: 29 de março, quarta-feira, às 12h10
Local: Sala de Seminários José Roberto Leite Ed. Alessandro Volta (bloco C) – Sala 110, IFUSP.
Abstract:
A quantum spin liquid (QSL) is an exotic state of matter in which electrons’ spins are quantum entangled over long distances, but do not show magnetic order in the zero-temperature limit1 . The observation of QSL states is a central aim of experimental physics, because they host collective excitations that transcend our knowledge of quantum matter; however, examples in real materials are scarce2 . Here, we report neutronscattering experiments on YbMgGaO4, a QSL candidate in which Yb3+ ions with effective spin-1/2 occupy a triangular lattice3, 4, 5, 6 . Our measurements reveal a continuum of magnetic excitations—the essential experimental hallmark of a QSL7 —at very low temperature (0.06 K). The origin of this peculiar excitation spectrum is a crucial question, because isotropic nearest-neighbour interactions do not yield a QSL ground state on the triangular lattice8 . Using measurements in the field-polarized state, we identify antiferromagnetic next-nearest-neighbour interactions9, 10, 11, 12, spin-space anisotropies4, 10, 13, 14, and chemical disorder15 between the magnetic layers as key ingredients in YbMgGaO4. http://www.nature.com/nphys/journal/v13/n2/full/nphys3971.html
