Composition-tuned smeared phase transitions

Hrahsheh, Fawaz; Nozadze, David; Vojta, Thomas

doi:10.1103/physrevb.83.224402

Cited by 14 publications

(24 citation statements)

References 21 publications

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“…31) In the previous paper, 23) we discussed the properties of the cluster-glass states in Sr 1−x La x RuO 3 based on the optimal fluctuation theory combined with a finite-size scaling technique. 32) This theory assumes that the magnetic property of a local region is characterized by the local La concentration and the size of the local region. If we assume a random distribution of Sr and La, the probability that a small region contains N La number of La atoms can be calculated using the binomial distribution P(N La ) = c is the critical concentration for the bulk system, D is a constant, and φ is the finite-size shift exponent.…”

Section: Discussionmentioning

confidence: 99%

Muon Spin Relaxation and Neutron Diffraction Studies of Cluster-Glass States in Sr₁₋_xLa_xRuO₃

et al. 2016

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To clarify the magnetic properties of cluster-glass states in Sr 1−x La x RuO 3 (0.3 ≤ x ≤ 0.5), we report herein the results of muon spin relaxation (µSR) and neutron powder diffraction measurements. The µSR experiments showed that magnetic clusters start developing well above the peak temperature T * in the ac susceptibility. The volume fraction of the magnetically ordered region increases continuously with decreasing temperature, showing no anomaly at T * , and reaches nearly 100% at the lowest temperature. The temperature variation of the volume fraction is essentially independent of the La concentration in the x range presently investigated, although the dc magnetization is significantly suppressed with increasing x. Neutron powder diffraction experiments revealed that the ground state for x = 0.3 is a long-range ferromagnetic ordered state. These results indicate that, with decreasing temperature, cluster-glass states in Sr 1−x La x RuO 3 gradually develop into long-range ferromagnetic ordered states with decreasing temperature, and that the magnetic ordering process differs strikingly from that expected for a conventional second-order ferromagnetic transition. IntroductionIn general, the 4d orbitals in 4d transition-metal oxides are more delocalized than the 3d orbitals in 3d transition-metal oxides; therefore, a conventional band picture is considered a suitable starting point for understanding such 4d electronic states. However, 4d transition-metal oxides exhibit a variety of intriguing electronic properties, such as quantum criticality, 1, 2) non-Fermi liquid behavior, 3) and unconventional superconductivity.4) These intriguing electronic properties imply that the correlation effect of 4d electrons is important, and that the electronic states are not trivial.Although 4d transition-metal oxides rarely show magnetic ordering, SrRuO 3 exhibits ferromagnetic order below T C = 160 K, and the ordered moment is approximately 1.1 µ B .

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Section: Discussionmentioning

confidence: 99%

Muon Spin Relaxation and Neutron Diffraction Studies of Cluster-Glass States in Sr₁₋_xLa_xRuO₃

et al. 2016

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“…Recently, the nature of the cluster size distribution is argued on the basis of the optimal fluctuation theory combined with the finite size scaling technique. 56) Let us focus on a small region in a sample where the total number of the Sr and La sites is N, and L RR is its linear size. For a given x value, the probability that the small region contains the N La number of La atoms is given by the binomial distribution P(N La ) = N N La x N La (1− x) N−N La .…”

Section: Discussionmentioning

confidence: 99%

Ferromagnetic Cluster-Glass State in Itinerant Electron System Sr₁₋_xLa_xRuO₃

et al. 2014

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The magnetic and electronic properties of Sr 1−x La x RuO 3 were studied by means of dc-magnetization, acsusceptibility, specific heat, and electrical resistivity measurements. The dc-magnetization and ac-susceptibility measurements have revealed that the transition temperature and the ordered moment of the ferromagnetic order are strongly suppressed as La is substituted for Sr. The ac-susceptibility exhibits a peak at T * due to the occurrence of spontaneous spin polarization. Furthermore, we observed that T * shows clear frequency variations for x ≥ 0.3. The magnitude of the frequency shifts of T * is comparable to that of cluster-glass systems, and the frequency dependence is well described in terms of the Vogel-Fulcher law. On the other hand, it is found that the linear specific heat coefficient γ enhances with the suppression of the ferromagnetic order. The relatively large γ values reflect the presence of the Ru 4d state at Fermi level, and hence, the magnetism of this system is considered to be tightly coupled with the itinerant characteristics of the Ru 4d electrons. The present experimental results and analyses suggest that the intrinsic coexistence of the spatially inhomogeneous magnetic state and the itinerant nature of the Ru 4d electrons is realized in this system, and such a feature may be commonly involved in La-and Ca-doped SrRuO 3 .

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“…[79]). magnetization tail behaves exponentially at intermediate p but vanishes as a power-law for p → 1 [80,81]. 32 is identical to (27), the bath Hamiltonian takes the form…”

Section: Optimal Fluctuation Theorymentioning

confidence: 99%

Phases and phase transitions in disordered quantum systems

Vojta

2013

AIP Conference Proceedings

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These lecture notes give a pedagogical introduction to phase transitions in disordered quantum systems and to the exotic Griffiths phases induced in their vicinity. We first review some fundamental concepts in the physics of phase transitions. We then derive criteria governing under what conditions spatial disorder or randomness can change the properties of a phase transition. After introducing the strong-disorder renormalization group method, we discuss in detail some of the exotic phenomena arising at phase transitions in disordered quantum systems. These include infinite-randomness criticality, rare regions and quantum Griffiths singularities, as well as the smearing of phase transitions. We also present a number of experimental examples.Comment: Pedagogical introduction to strong disorder physics at quantum phase transitions. Based on lectures given at the XVII Training Course in the Physics of Strongly Correlated Systems in Vietri sul Mare, Italy in October 2012. Submitted to the proceedings of this school. 60 pages and 23 figures. Builds on material reviewed in arXiv:cond-mat/0602312 and arXiv:1005.270

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Composition-tuned smeared phase transitions

Cited by 14 publications

References 21 publications

Muon Spin Relaxation and Neutron Diffraction Studies of Cluster-Glass States in Sr₁₋_xLa_xRuO₃

Muon Spin Relaxation and Neutron Diffraction Studies of Cluster-Glass States in Sr₁₋_xLa_xRuO₃

Ferromagnetic Cluster-Glass State in Itinerant Electron System Sr₁₋_xLa_xRuO₃

Phases and phase transitions in disordered quantum systems

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Composition-tuned smeared phase transitions

Cited by 14 publications

References 21 publications

Muon Spin Relaxation and Neutron Diffraction Studies of Cluster-Glass States in Sr1−xLaxRuO3

Muon Spin Relaxation and Neutron Diffraction Studies of Cluster-Glass States in Sr1−xLaxRuO3

Ferromagnetic Cluster-Glass State in Itinerant Electron System Sr1−xLaxRuO3

Phases and phase transitions in disordered quantum systems

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Muon Spin Relaxation and Neutron Diffraction Studies of Cluster-Glass States in Sr₁₋_xLa_xRuO₃

Muon Spin Relaxation and Neutron Diffraction Studies of Cluster-Glass States in Sr₁₋_xLa_xRuO₃

Ferromagnetic Cluster-Glass State in Itinerant Electron System Sr₁₋_xLa_xRuO₃