Spin excitations in the two-dimensional strongly coupled dimer system malachite

Emmanuel Canevet (1, 2) , Bjorn Fak (3, 2) , R. K. Kremer , J. H. Chun , M. Enderle (2) , E. E. Gordon (4) , J. L. Bettis (4) , M. H. Whangbo (4) , J. W. Taylor (5) , D. T. Adroja (5)

1 UP11 - Université Paris-Sud - Paris 11
2 ILL - Institut Laue-Langevin
3 IMAPEC - Instrumentation, Material and Correlated Electrons Physics
4 NC State - North Carolina State University [Raleigh]
5 ISIS Facility

The mineral malachite, Cu-2(OD)(2)CO3, has a quantum spin-liquid ground state and no long-range magnetic order down to at least T = 0.4 K. Inelastic neutron scattering measurements show that the excitation spectrum consists of dispersive gapped singlet-triplet excitations, characteristic of spin-1/2 dimer-forming Heisenberg antiferromagnets. We identify a distinct two-dimensional dimerized coupling scheme with strong interdimer coupling J'/J(1) approximate to 0.3 that places malachite between strongly coupled alternating chains, square lattice antiferromagnets, and infinite-legged ladders. The geometry of the interaction scheme resembles the staggered dimer lattice, which may allow unconventional quantum criticality.

Mots clés: Augmented-Wave Method; Antiferromagnet; Azurite; Cu2(OH)2Co3; Chains; Model

Domaines: Physique [physics]

Emmanuel Canevet, Bjorn Fak, R. K. Kremer, J. H. Chun, M. Enderle, et al.. Spin excitations in the two-dimensional strongly coupled dimer system malachite. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2015, 91 (6), pp.060402. ⟨10.1103/PhysRevB.91.060402⟩. ⟨hal-01588139⟩