TY - JOUR

T1 - Non-collinearity Effects on Magnetocrystalline Anisotropy for R2Fe14B Magnets

AU - Miura, Daisuke

AU - Sakuma, Akimasa

N1 - Funding Information:
Acknowledgments We would like to thank Professor H. Kato, Dr. Y. Toga, and Mr. D. Suzuki for useful discussions and information. This work was supported by JSPS KAKENHI Grant Nos. 16K06702, 16H02390, 16H04322, and 17K14800.
Publisher Copyright:
©2019 The Physical Society of Japan

PY - 2019

Y1 - 2019

N2 - We present a theoretical investigation of the magnetocrystalline anisotropy (MA) in R2Fe14B (R is a rare-earth element) magnets in consideration of the non-collinearity effect (NCE) between the R and Fe magnetization directions. In particular, the temperature dependence of the MA of Dy2Fe14B magnets is detailed in terms of the nth-order MA constant (MAC) Kn(T) at a temperature T. The features of this constant are as follows: K1(T) has a broad plateau in the low-temperature range and K2(T) persistently survives in the high-temperature range. The present theory explains these features in terms of the NCE on the MA by using numerical calculations for the entire temperature range, and further, by using a high-temperature expansion. The high-temperature expansion for Kn(T) is expressed in the form of Kn(T) = κ1(T) [1 + δ(T)][−δ(T)]n−1, where κ1(T) is the part without the NCE and δ(T) is a correction factor for the NCE introduced in this study. We also provide a convenient expression to evaluate Kn(T), which can be determined only by a second-order crystalline electric field coefficient and an effective exchange field.

AB - We present a theoretical investigation of the magnetocrystalline anisotropy (MA) in R2Fe14B (R is a rare-earth element) magnets in consideration of the non-collinearity effect (NCE) between the R and Fe magnetization directions. In particular, the temperature dependence of the MA of Dy2Fe14B magnets is detailed in terms of the nth-order MA constant (MAC) Kn(T) at a temperature T. The features of this constant are as follows: K1(T) has a broad plateau in the low-temperature range and K2(T) persistently survives in the high-temperature range. The present theory explains these features in terms of the NCE on the MA by using numerical calculations for the entire temperature range, and further, by using a high-temperature expansion. The high-temperature expansion for Kn(T) is expressed in the form of Kn(T) = κ1(T) [1 + δ(T)][−δ(T)]n−1, where κ1(T) is the part without the NCE and δ(T) is a correction factor for the NCE introduced in this study. We also provide a convenient expression to evaluate Kn(T), which can be determined only by a second-order crystalline electric field coefficient and an effective exchange field.

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U2 - 10.7566/JPSJ.88.044804

DO - 10.7566/JPSJ.88.044804

M3 - Article

AN - SCOPUS:85067242263

VL - 88

JO - Journal of the Physical Society of Japan

JF - Journal of the Physical Society of Japan

SN - 0031-9015

IS - 4

M1 - 044804

ER -