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arXiv 1007.4021cond-mat.str-el
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非常规反铁磁化合物Yb3Pt4的磁跃迁和自旋涨落

Magnetic transition and spin fluctuations in the unconventional antiferromagnetic compound Yb3Pt4

S. Zhao, D. E. MacLaughlin, O. O. Bernal, J. M. Mackie, C. Marques, Y. Janssen, M. C. Aronson

摘要:

对非常规反铁磁体Yb_3Pt_4进行了μ子自旋旋转和弛豫测量。在T_N = 2.22(1)K以下观察到振荡,与体实验中观察到的反铁磁(AFM)Neel温度一致。与中子衍射实验一致,振荡频率ω_ mu(T)遵循S = 1/2的平均场温度依赖关系,在T = 0时产生准静态局域场1.71(2)kOe。粗略估计在T = 0时的有序矩约为0.66 μ B,与中子衍射的0.81 μ B相当。当T从上面接近T_N时,动态弛豫速率λ_d没有表现出临界减慢,与平均场跃迁一致。在原子力显微镜阶段,对λ_d(T)进行T-线性拟合,适合于费米液体,得到了高度增强的λ_d/T值和柯林加常数K_mu ^2 T/λ_d,K_ mu是估计的μ介子奈特位移。在AFM阶段观察到外加场对λ_d的强烈抑制。这些性质与在Yb_3Pt_4中观察到的大的Sommercil-Wilson和Kadowaki-Woods比相一致(尽管数据不能区分费米液体和非费米液体状态),并且表明在Yb_3Pt_4的AFM相中大费米体积带准粒子之间的q ~ 0自旋关联强烈增强。

英文摘要:

Muon spin rotation and relaxation measurements have been carried out on the unconventional antiferromagnet Yb_3Pt_4. Oscillations are observed below T_N = 2.22(1) K, consistent with the antiferromagnetic (AFM) Neel temperature observed in bulk experiments. In agreement with neutron diffraction experiments the oscillation frequency omega_ mu(T) follows a S = 1/2 mean-field temperature dependence, yielding a quasistatic local field 1.71(2) kOe at T = 0. A crude estimate gives an ordered moment of ~0.66 mu_B at T = 0, comparable to 0.81 mu_B from neutron diffraction. As T approaches T_N from above the dynamic relaxation rate lambda_d exhibits no critical slowing down, consistent with a mean-field transition. In the AFM phase a T-linear fit to lambda_d(T), appropriate to a Fermi liquid, yields highly enhanced values of lambda_d/T and the Korringa constant K_ mu^2 T/lambda_d, with K_ mu the estimated muon Knight shift. A strong suppression of lambda_d by applied field is observed in the AFM phase. These properties are consistent with the observed large Sommerfeld-Wilson and Kadowaki-Woods ratios in Yb_3Pt_4 (although the data do not discriminate between Fermi-liquid and non-Fermi-liquid states), and suggest strong enhancement of q ~ 0 spin correlations between large-Fermi-volume band quasiparticles in the AFM phase of Yb_3Pt_4.

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