TY - JOUR
T1 - Multistage ordering and critical singularities in Co1-x Z nx A l2 O4(0≤x≤1)
T2 - Dilution and pressure effects in a magnetically frustrated system
AU - Naka, Takashi
AU - Sato, Koichi
AU - Matsushita, Yoshitaka
AU - Terada, Noriki
AU - Ishii, Satoshi
AU - Nakane, Takayuki
AU - Taguchi, Minori
AU - Nakayama, Minako
AU - Hashishin, Takeshi
AU - Ohara, Satoshi
AU - Takami, Seiichi
AU - Matsushita, Akiyuki
N1 - Publisher Copyright:
© 2015 American Physical Society.
PY - 2015/6/9
Y1 - 2015/6/9
N2 - We report comprehensive studies of the crystallographic, magnetic, and thermal properties of a spinel-type magnetically frustrated compound, CoAl2O4, and a magnetically diluted system, Co1-xZnxAl2O4. These studies revealed the effects of dilution and disorder when the tetrahedral magnetic Co ion was replaced by the nonmagnetic Zn ion. Low-temperature anomalies were observed in magnetic susceptibility at x<0.6. A multicritical point was apparent at T=3.4K and x=0.12, where the antiferromagnetic, spin-glass-like, and paramagnetic phases met. At that point, the quenched ferromagnetic component induced by a magnetic field during cooling was sharply enhanced and was observable below x=0.6. At x∼0.6, magnetic susceptibility and specific heat were described by temperature power laws, χ∼C/T∼T-δ, in accord with the site percolation threshold of the diamond lattice. This behavior is reminiscent of a quantum critical singularity. We propose an x-temperature phase diagram in the range 0≤x≤1 for Co1-xZnxAl2O4. The transition temperature of CoAl2O4 determined from magnetic susceptibility measured under hydrostatic pressure increased with increasing pressure.
AB - We report comprehensive studies of the crystallographic, magnetic, and thermal properties of a spinel-type magnetically frustrated compound, CoAl2O4, and a magnetically diluted system, Co1-xZnxAl2O4. These studies revealed the effects of dilution and disorder when the tetrahedral magnetic Co ion was replaced by the nonmagnetic Zn ion. Low-temperature anomalies were observed in magnetic susceptibility at x<0.6. A multicritical point was apparent at T=3.4K and x=0.12, where the antiferromagnetic, spin-glass-like, and paramagnetic phases met. At that point, the quenched ferromagnetic component induced by a magnetic field during cooling was sharply enhanced and was observable below x=0.6. At x∼0.6, magnetic susceptibility and specific heat were described by temperature power laws, χ∼C/T∼T-δ, in accord with the site percolation threshold of the diamond lattice. This behavior is reminiscent of a quantum critical singularity. We propose an x-temperature phase diagram in the range 0≤x≤1 for Co1-xZnxAl2O4. The transition temperature of CoAl2O4 determined from magnetic susceptibility measured under hydrostatic pressure increased with increasing pressure.
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U2 - 10.1103/PhysRevB.91.224412
DO - 10.1103/PhysRevB.91.224412
M3 - Article
AN - SCOPUS:84931275436
VL - 91
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
SN - 0163-1829
IS - 22
M1 - 224412
ER -