Open AccessChemical and physical pressure effects in the A-site spinel antiferromagnets CoM2O4 (M = Al, Co, and Rh)
Author(s) -
Takashi Naka,
Jaroslav Valenta,
J. Kaštil,
M. Míšek,
J. Prchal,
V. Sechovský,
Hiroya Abe,
T. Nakane,
Minako Nakayama,
Tetsuo Uchikoshi
Publication year - 2020
Publication title -
materials research express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.383
H-Index - 35
ISSN - 2053-1591
DOI - 10.1088/2053-1591/ab924f
Subject(s) - antiferromagnetism , isostructural , spinel , hydrostatic pressure , phase transition , ambient pressure , atmospheric temperature range , chemistry , heat capacity , crystallography , materials science , crystal structure , analytical chemistry (journal) , thermodynamics , condensed matter physics , physics , metallurgy , chromatography
Magnetic phase transitions under high pressure are reported for the diamond lattice antiferromagnet Co 3−x Rh x O 4 in the range of 0 ≤ x ≤ 2.0, which is an isostructural S = 3/2 system for the well-known frustrated antiferromagnet CoAl 2 O 4 . In the Co 3−x Rh x O 4 system, magnetic and specific-heat measurements at ambient pressure revealed that a second-order antiferromagnetic transition occurred at the Néel temperature ( T N ) which exhibits a nonmonotonic x -variation. The physical pressure variations of T N were determined by ac-calorimetry under hydrostatic pressures up to p = 2.6 GPa for Co 2 RhO 4 and CoRh 2 O 4 . The rates of change of T N with pressure (i.e., the pressure coefficients), 1.93 and 1.61 K GPa −1 , respectively, were comparable to those for CoAl 2 O 4 and Co 3 O 4 , respectively. The pressure coefficients of magnetic ordering temperature for these A-site spinel compounds were considerably larger than those for other spinel and iron-garnet compounds which follow the empirical ‘10/3 law’. Simple analysis of the chemical and physical pressure coefficients of T N revealed that T N depended on both the lattice volume and the oxygen positional parameter u .