Anand V K, Johnston D C
Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA. Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, D-14109 Berlin, Germany.
J Phys Condens Matter. 2014 Jul 16;26(28):286002. doi: 10.1088/0953-8984/26/28/286002. Epub 2014 Jun 19.
The physical properties of self-flux grown EuPd2As2 single crystals have been investigated by means of magnetization M, magnetic susceptibility χ, specific heat Cp, and electrical resistivity ρ measurements versus temperature T and magnetic field H. The crystal structure was determined using powder x-ray diffraction measurements, which confirmed the ThCr2Si2-type body-centered tetragonal structure (space group I4/mmm) reported previously. The ρ(T) data indicate that EuPd2As2 is metallic. The χ(T) data indicate that the Eu(+2) moments have spin S = 7/2 with g = 2. Long-range antiferromagnetic (AFM) ordering is apparent from the χ(T), Cp(T), and ρ(T) measurements. For H∥c the χ(T) indicates two transitions at TN1 = 11.0 K and TN2 = 5.5 K, whereas for H⊥c only one transition is observed at TN1 = 11.0 K. Between TN1 and TN2 the anisotropic χ(T) data suggest a planar noncollinear AFM structure, whereas at T < TN2 the χ(T) and M(H, T) data suggest a spin reorientation transition in which equal numbers of spins cant in opposite directions out of the ab plane. We estimate the critical field at 2 K at which all Eu moments become aligned with the field to be about 22 T. An upturn in ρ at T < TN1 suggests superzone energy gap formation below TN1. This behavior of ρ(T < TN1) is not sensitive to applied magnetic fields up to H = 12 T.
通过测量磁化强度(M)、磁化率(\chi)、比热(C_p)和电阻率(\rho)随温度(T)和磁场(H)的变化，研究了自熔剂生长的EuPd₂As₂单晶的物理性质。使用粉末X射线衍射测量确定了晶体结构，证实了先前报道的ThCr₂Si₂型体心四方结构（空间群I4/mmm）。(\rho(T))数据表明EuPd₂As₂是金属性的。(\chi(T))数据表明Eu(+2)磁矩的自旋(S = 7/2)，(g = 2)。从(\chi(T))、(C_p(T))和(\rho(T))测量中可以明显看出长程反铁磁（AFM）有序。对于(H\parallel c)，(\chi(T))表明在(T_{N1}=11.0K)和(T_{N2}=5.5K)处有两个转变，而对于(H\perp c)，仅在(T_{N1}=11.0K)处观察到一个转变。在(T_{N1})和(T_{N2})之间，各向异性的(\chi(T))数据表明是平面非共线AFM结构，而在(T < T_{N2})时，(\chi(T))和(M(H, T))数据表明存在自旋重取向转变，其中相等数量的自旋在(ab)平面外沿相反方向倾斜。我们估计在(2K)时所有Eu磁矩与磁场对齐的临界场约为(22T)。在(T < T_{N1})时(\rho)的上升表明在(T_{N1})以下形成了超区能隙。(\rho(T < T_{N1}))的这种行为对高达(H = 12T)的外加磁场不敏感。
