Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 41: Frustrated Magnets - Spin Liquids - Experiments

TT 41.9: Talk

Tuesday, March 13, 2018, 12:30–12:45, H 3005

Exploration of the quantum spin liquid state in Ca₁₀Cr₇O₂₈ — Christian Balz^1,2, •Bella Lake^1,3, ATM Nazmul Islam¹, Ulrich Tutsch⁴, Michael Lang⁴, Yuji Matsuda⁵, Lars Opherden^6,7, Thomas Herrmannsdoefer⁶, and Jose A. Rodriguez-Rivera⁸ — ¹Helmholtz Zentrum Berlin, Germany — ²Oak Ridge National Lab, USA — ³Technical University Berlin, Germany — ⁴Goethe University, Germany — ⁵Kyoto University, Japan — ⁶Helmholtz Zentrum Dresden Rossendorf, Germany — ⁷Technical University Dresden, Germany — ⁸NIST, MD, USA

Ca₁₀Cr₇O₂₈ is a new candidate spin liquid where the magnetic Cr⁵⁺ ions (S-1/2) form breathing Kagome bilayers. Both kagome layers consist of alternating ferromagnetic/antiferromagnetic corner-sharing triangles and the two layers are stacked so that the ferromagnetic triangles lie on top of antiferromagnetic triangles and vice versa. Previous measurements revealed the absence of long-range magnetic order and the presence of persistent spin dynamics in the ground state. Here we present a detailed exploration of the ground state and excitations using magnetisation, heat capacity, thermal conductivity and inelastic neutron scattering. The heat capacity and thermal conductivity are linear in temperature suggesting the presence of a gapless spinon Fermi surface while the excitations are diffuse revealing the presence of spinon continuua. The excitations appear gapless and form a distinct pattern that evolves gradually with energy. Together these results provide strong evidence that Ca₁₀Cr₇O₂₈ is a gapless quantum spin liquid. The origins of this spin liquid state will be discussed.