Quantum Critical Point of Itinerant Antiferromagnet in the Heavy Fermion Ce(Ru_{1-x}Rh_x)_2Si_2

A focus of recent experimental and theoretical studies on heavy fermion systems close to antiferromagnetic (AFM) quantum critical points (QCP) is directed toward revealing the nature of the fixed point, i.e., whether it is an itinerant antiferromagnet [spin density wave (SDW)] type or a locally-critical fixed point. The relevance of the local QCP was proposed to explain the E/T-scaling with an anomalous exponent observed for the AFM QCP of CeCu_{5.9}Au_{0.1}. In this work, we have investigated an AFM QCP of another archetypal heavy fermion system Ce(Ru_{1-x}Rh_x)_2Si_2 with x = 0 and 0.03 (sim x_c) using single-crystalline neutron scattering. Accurate measurements of the dynamical susceptibility Im[chi(Q,E)] at the AFM wave vector Q = 0.35 c^* have shown that Im[chi(Q,E)] is well described by a Lorentzian and its energy width Gamma(Q), i.e., the inverse correlation time depends on temperature as Gamma(Q) = c_1 + c_2 T^{3/2 +- 0.1}, where c_1 and c_2 are x dependent constants, in low temperature ranges.This critical exponent 3/2 proves that the QCP is controlled by the SDW QCP in three space dimensions studied by the renormalization group and self-consistent renormalization theories.Comment: 4 pages, 4 figures, LT24 (Aug. 2005, Orlando

Quantum Critical Point of Itinerant Antiferromagnet in Heavy Fermion

A quantum critical point (QCP) of the heavy fermion Ce(Ru_{1-x}Rh_x)_2Si_2 (x = 0, 0.03) has been studied by single-crystalline neutron scattering. By accurately measuring the dynamical susceptibility at the antiferromagnetic wave vector k_3 = 0.35 c^*, we have shown that the energy width Gamma(k_3), i.e., inverse correlation time, depends on temperature as Gamma(k_3) = c_1 + c_2 T^{3/2 +- 0.1}, where c_1 and c_2 are x dependent constants, in a low temperature range. This critical exponent 3/2 +- 0.1 proves that the QCP is controlled by that of the itinerant antiferromagnet.Comment: 4 pages, 3 figure

FeSi - CoSiケイノジセイニカンスルケンキュウ

京都大学0048新制・課程博士工学博士甲第1245号工博第305号新制||工||226(附属図書館)3310UT51-47-K19京都大学大学院工学研究科金属加工学専攻(主査)教授 中村 陽二, 教授 高村 仁一, 教授 森本 武学位規則第5条第1項該当Kyoto UniversityDA

Neutron Scattering Studies of the Magnetic Ordering in Ternary Rare Earth Compounds

Neutron scattering results on a series of materials in the pseudoternary alloy system (Er,Ho)Rh4B4 are discussed. A wide range of behavior is found for the magnetic transitions for various compositions. The Ho rich materials are understood best, with mean-field transitions taking place in the nonsuperconducting materials and sharp first order phase boundaries occuring between magnetism and superconductivity in the reentrant materials. The competition between superconductivity and magnetism makes the magnetic ordering very complex in ErRh4B4 and a number of experiments have been performed to study this transition. Even more complex behavior is found near the multicritical point in the alloy phase diagram with more than one type of transition being observed

Superconductivity and Magnetism in Ternary Rare-earth Compounds

Superconductivity and magnetism are two types of order that can take place in materials at low temperatures. When the magnetic order is ferromagnetic, a competition exists between magnetism and superconductivity. Neutron scattering has been used to measure the interaction of magnetism and superconductivity in a series of ternary rare-earth alloys. A wide range of behavior is found near the magnetic transition, including mean-field magnetic ordering, first-order transitions between magnetism and superconductivity, and co-existence of ferromagnetism and superconductivity with a sinusoidally-modulated magnetic phase