Quantum phase transitions in single-crystal Mn1-xFexSi and Mn1-xCoxSi: Crystal growth, magnetization, ac susceptibility, and specific heat
Quantum phase transitions in single-crystal Mn1-xFexSi and Mn1-xCoxSi: Crystal growth, magnetization, ac susceptibility, and specific heat
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DOI：
10.1103/physrevb.82.064404
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发表时间：
2010-08-04
影响因子：
3.7
通讯作者：
Pfleiderer, C.
中科院分区：
文献类型：
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作者：
Bauer, A.;Neubauer, A.;Pfleiderer, C.
我们报道了光学浮区单晶Mn1-xFexSi和Mn1-xCoxSi的磁化强度、交流磁化率和比热，温度降到2K以下，磁场高达9T。从磁化强度、交流磁化率和比热可以看出，在临界成分x(1)以上的日磁转变温度T-1被抑制，表明x(1)处存在量子相变。可归因于Dzyaloshinsky-Moriya(DM)自旋-轨道相互作用的Vollhardt不变性在温度T-2和T-1处也随着x的增加而被抑制，并且在浓度x(2)以上消失，其中x(2)>；x(1)。当抑制外加磁场中DM相互作用的影响时，足够大的场的磁化与对于临界浓度x(C)的潜在铁磁量子临界点的预期签名相同，其中x(1)<；x(C)<；x(2)。作为归一化浓度x/x(C)的函数，其中x(C)(Co)接近0.084，x(C)(Fe)接近0.192，Mn1-xFexSi和Mn1-xCoxSi的性质基本相同，x(1)/x(C)接近0.78，x(2)/x(C)接近1.17.综上所述，我们的研究确定了Mn1-xFexSi和Mn1-xCoxSi是可以研究DM相互作用对铁磁量子临界性影响的模型系统。
We report the magnetization, ac susceptibility, and specific heat of optically float-zoned single crystals of Mn1-xFexSi and Mn1-xCoxSi for temperatures down to similar to 2 K and magnetic fields up to 9 T. The suppression of the helimagnetic transition temperature T-1 above a critical composition x(1), as seen in the magnetization, ac susceptibility, and specific heat, suggests the existence of a quantum phase transition at x(1). A Vollhardt invariance at a temperature T-2 > T-1, which may be attributed to the Dzyaloshinsky-Moriya (DM) spin-orbit interactions, is also suppressed with increasing x and vanishes above a concentration x(2), where x(2) > x(1). When suppressing the effects of the DM interactions in an applied magnetic field, the magnetization for sufficiently large fields shares the signatures expected of an underlying putative ferromagnetic quantum critical point for a critical concentration x(c), where x(1) < x(c) < x(2). As a function of normalized concentration x/x(c), where x(c)(Co) approximate to 0.084 and x(c)(Fe) approximate to 0.192, the properties of Mn1-xFexSi and Mn1-xCoxSi are essentially identical with x(1)/x(c) approximate to 0.78 and x(2)/x(c) approximate to 1.17. Taken together, our study identifies Mn1-xFexSi and Mn1-xCoxSi as model systems in which the influence of DM interactions on ferromagnetic quantum criticality may be studied.