Novák V, Olejník K, Wunderlich J, Cukr M, Výborný K, Rushforth A W, Edmonds K W, Campion R P, Gallagher B L, Sinova Jairo, Jungwirth T
Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic.
Phys Rev Lett. 2008 Aug 15;101(7):077201. doi: 10.1103/PhysRevLett.101.077201. Epub 2008 Aug 12.
We observe a singularity in the temperature derivative drho/dT of resistivity at the Curie point of high-quality (Ga,Mn)As ferromagnetic semiconductors with Tc's ranging from approximately 80 to 185 K. The character of the anomaly is sharply distinct from the critical contribution to transport in conventional dense-moment magnetic semiconductors and is reminiscent of the drho/dT singularity in transition metal ferromagnets. Within the critical region accessible in our experiments, the temperature dependence on the ferromagnetic side can be explained by dominant scattering from uncorrelated spin fluctuations. The singular behavior of drho/dT on the paramagnetic side points to the important role of short-range correlated spin fluctuations.
我们在高质量的（Ga，Mn）As铁磁半导体的居里点观察到电阻率的温度导数drho/dT出现奇异性，其居里温度Tc范围约为80至185K。这种异常的特征与传统致密磁矩磁半导体中对输运的临界贡献明显不同，让人联想到过渡金属铁磁体中的drho/dT奇异性。在我们实验可及的临界区域内，铁磁侧的温度依赖性可以用不相关自旋涨落的主导散射来解释。顺磁侧drho/dT的奇异行为表明短程相关自旋涨落起着重要作用。
