Coexistence of singlet and ordered S=12 moments in the ground state of the triclinic quantum magnet CuMoO4

Published

Journal Article

CuMoO4 is a triclinic quantum magnet based on S=1/2 moments at the Cu2+ site. It has recently attracted interest due to the remarkable changes in its chromic and volumetric properties at high temperatures and in its magnetic properties at low temperatures. This material exhibits a first-order structural phase transition at TC ∼ 190 K as well as a magnetic phase transition at TN ∼ 1.75 K. We report low-temperature heat capacity measurements as well as extensive elastic and inelastic neutron scattering measurements on powder samples taken above and below TN. We observe neutron diffraction consistent with a simple (1/2, 0, 0) antiferromagnetic structure indicating a doubling of the a-axis periodicity below TN. In addition, inelastic neutron scattering above a spin gap of ∼2.3 meV is consistent with triplet excitations out of paired S=1/2 moments which form singlet dimers. Low-lying spin wave excitations are also observed and these originate from ordered S=1/2 moments below T N. Taken together these measurements show the ground state of CuMoO4 to display both nonmagnetic singlets and ferromagnetically coupled spins coexisting within an antiferromagnetic structure below T N ∼ 1.75 K. © 2011 American Physical Society.

Full Text

Duke Authors

Cited Authors

  • Haravifard, S; Fritsch, K; Asano, T; Clancy, JP; Yamani, Z; Ehlers, G; Nishimura, T; Inagaki, Y; Kawae, T; Swainson, I; Gaulin, BD

Published Date

  • September 22, 2011

Published In

Volume / Issue

  • 84 / 9

Electronic International Standard Serial Number (EISSN)

  • 1550-235X

International Standard Serial Number (ISSN)

  • 1098-0121

Digital Object Identifier (DOI)

  • 10.1103/PhysRevB.84.094436

Citation Source

  • Scopus