Observation of long-range magnetic ordering in pyrohafnate Nd2Hf2O7: A neutron diffraction study
Observation of long-range magnetic ordering in pyrohafnate Nd2Hf2O7: A neutron diffraction study
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DOI：
10.1103/physrevb.92.184418
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发表时间：
2015-11-18
影响因子：
3.7
通讯作者：
Lake, B.
中科院分区：
文献类型：
--
作者：
Anand, V. K.;Bera, A. K.;Lake, B.
用交流磁化率chi(Ac)(T)、直流磁化率chi(T)、等温磁化强度M(H)和热容C-p(T)研究了烧绿石Nd2Hf2O7的物理性质，并用中子粉末衍射法确定了其磁基态。C-p(T)/T在6K以下有一个反转，而C-p(T)和chi(T)在2K以下都没有明显的反常现象，而chi(Ac)(T)在T-N=0.55K有明显的反铁磁转变，中子衍射证实了长程反铁磁有序。对中子衍射图的修正揭示了一种Allin/All-Out反铁磁结构，其中对于连续的四面体，四个Nd3+磁矩交替地指向四面体的全入或全出，其有序波矢k=(0，0，0)，在0.1K时的有序态磁矩m=0.62(1)Mu(B)/Nd，有序矩强烈地减少，反映了有序态的强烈量子涨落。
We have investigated the physical properties of a pyrochlore hafnate Nd2Hf2O7 using ac magnetic susceptibility chi(ac)(T), dc magnetic susceptibility chi(T), isothermal magnetization M(H), and heat capacity C-p(T) measurements, and determined the magnetic ground state by neutron powder diffraction. An upturn is observed below 6 K in C-p(T)/T, however both C-p(T) and chi(T) do not show any clear anomaly down to 2 K. The chi(ac)(T) shows a well-pronounced anomaly indicating an antiferromagnetic transition at T-N = 0.55 K. The long-range antiferromagnetic ordering is confirmed by neutron diffraction. The refinement of the neutron diffraction pattern reveals an allin/all- out antiferromagnetic structure, where for successive tetrahedra the four Nd3+ magnetic moments point alternatively all-into or all-out-of the tetrahedron, with an ordering wave vector k = (0, 0, 0) and an ordered state magnetic moment of m = 0.62(1) mu(B)/Nd at 0.1 K. The ordered moment is strongly reduced, reflecting strong quantum fluctuations in ordered state.