Lattice-site-specific spin dynamics in double perovskite Sr2CoOsO6.
Magnetic properties and spin dynamics have been studied for the structurally ordered double perovskite Sr2CoOsO6. Neutron diffraction, muon-spin relaxation, and ac-susceptibility measurements reveal two antiferromagnetic (AFM) phases on cooling from room temperature down to 2 K. In the first AFM phase, with transition temperature TN1=108  K, cobalt (3d7, S=3/2) and osmium (5d2, S=1) moments fluctuate dynamically, while their average effective moments undergo long-range order. In the second AFM phase below TN2=67  K, cobalt moments first become frozen and induce a noncollinear spin-canted AFM state, while dynamically fluctuating osmium moments are later frozen into a randomly canted state at T≈5  K. Ab initio calculations indicate that the effective exchange coupling between cobalt and osmium sites is rather weak, so that cobalt and osmium sublattices exhibit different ground states and spin dynamics, making Sr2CoOsO6 distinct from previously reported double-perovskite compounds.
Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany and Max-Planck-Institut für Physik komplexer Systeme, 01187 Dresden, Germany.
Binghai
B
Yan
Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany.
Avijit Kumar
AK
Paul
Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany.
Sudipta
S
Kanungo
Helmholtz-Zentrum für Materialien und Energie, 14109 Berlin, Germany.
Manfred
M
Reehuis
Helmholtz-Zentrum für Materialien und Energie, 14109 Berlin, Germany.
Andreas
A
Hoser
Helmholtz-Zentrum für Materialien und Energie, 14109 Berlin, Germany.
Daniel M
DM
Többens
Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany.
Walter
W
Schnelle
Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom.
Robert C
RC
Williams
Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom.
Tom
T
Lancaster
Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom.
Fan
F
Xiao
Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
Johannes S
JS
Möller
Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
Stephen J
SJ
Blundell
Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
William
W
Hayes
Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany and Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität, 55128 Mainz, Germany.
Claudia
C
Felser
Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany and Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany.
Martin
M
Jansen