Easy-plane magnetocrystalline anisotropy in the multi-step metamagnet CeIr3Si2
K. Shigetoh, A. Ishida, Y. Ayabe, T. Onimaru, K. Umeo, Y. Muro, K. Motoya, M. Sera, T. Takabatake
Abstract
Highly anisotropic properties of CeIr
3
Si
2
have been observed by the magnetization
M
(
B
), electrical resistivity
ρ
, and specific heat measurements on a single-crystalline sample. This compound with an orthorhombic structure having zigzag chains of Ce ions along the a-axis undergos magnetic transitions at 3.9 K and 3.1 K. At 0.3 K, metamagnetic transitions occur at 0.68 T and 1.3 T for
B
//
b
and 0.75 T for
B
//
c
. Easy-plane magnetocrystalline anisotropy is manifested as
M
(
B//b
)
≅
M
(
B//c
)
≅
11
M
(
B//a
) at
B
= 5 T. Electrical resistivity is also anisotropic;
ρ
b
≅
ρ
c
≥
2
ρ
a
. The magnetic part of
ρ
exhibits a double-peak structure with maxima at 15 K and 250 K. The magnetic entropy at
T
N1
= 3.9 K is a half of
R
ln2. These observations are ascribable to the combination of the Kondo effect with
T
K
∼
20 K and a strong crystal field effect. The analysis of
M
(
B
) and paramagnetic susceptibility revealed unusually large energy splitting of 500 K and 1600 K for the two excited doublets, respectively.