Anomalously large spin-dependent electron correlation in the nearly half-metallic ferromagnet CoS2-猫眼课题宝

DOI：

10.1103/physrevb.106.085114

发表时间：

2022-08

期刊：

Physical Review B

影响因子：

3.7

通讯作者：

中科院分区：

物理与天体物理2区

文献类型：

作者：

H. Fujiwara;K. Terashima;Junya Otsuki;Nayuta Takemori;Harald O. Jeschke;T. Wakita;Y. Yano;W. Hosoda;Noriyuki Kataoka;A. Teruya;M. Kakihana;M. Hedo;T. Nakama;Y. Ōnuki;K. Yaji;A. Harasawa;K. Kuroda;Shik Shin;K. Horiba;H. Kumigashira;Y. Muraoka;T. Yokoya

通过自旋和角分辨光电子能谱以及理论计算，研究了半金属铁磁体候选化合物CoS$_2$的自旋相关能带结构，以重新评价半金属性和电子相关性。我们确定了三维费米面和自旋相关的能带结构。结果发现，在费米能级附近，少数自旋带的一部分位于占据的一侧，这为CoS$_2$不是半金属但非常接近半金属提供了光谱证据.用密度泛函理论和广义梯度近似的能带计算结果与观测到的多数自旋eg带吻合得很好，但不能解释少数自旋eg带的带宽。另一方面，用动力学平均场理论计算能更好地再现少数自旋e_g带中的强质量重整化。所有这些结果都有力地表明，在半金属态附近的电子结构上存在着强烈增强的自旋相关电子关联效应。我们还报道了电子结构随居里温度的变化，并讨论了热退磁的机理。我们的发现极大的自旋相关的电子关联不仅证明了理解半金属的电子结构的一个关键因素，但也提供了一个动机，以改善自旋极化强关联系统的理论计算。

The spin-dependent band structure of CoS$_2$ which is a candidate for a half-metallic ferromagnet was investigated by both spin- and angle-resolved photoemission spectroscopy and theoretical calculations, in order to reappraise the half-metallicity and electronic correlations. We determined the three-dimensional Fermi surface and the spin-dependent band structure. As a result, we found that a part of the minority spin bands is on the occupied side in the vicinity of the Fermi level, providing spectroscopic evidence that CoS$_2$ is not but very close to a half-metal. Band calculations using density functional theory with generalized gradient approximation showed a good agreement with the observed majority spin $e_g$ bands, while it could not explain the observed band width of the minority-spin eg bands. On the other hand, theoretical calculations using dynamical mean field theory could better reproduce the strong mass renormalization in the minority-spin $e_g$ bands. All those results strongly suggest the presence of anomalously enhanced spin-dependent electron correlation effects on the electronic structure in the vicinity of the half-metallic state. We also report the temperature dependence of the electronic structure across the Curie temperature and discuss the mechanism of the thermal demagnetization. Our discovery of the anomalously large spin-dependent electronic correlations not only demonstrates a key factor in understanding the electronic structure of half-metals but also provides a motivation to improve theoretical calculations on spin-polarized strongly correlated systems.

Anomalously large spin-dependent electron correlation in the nearly half-metallic ferromagnet CoS2

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