Avoided quantum criticality and cluster-glass formation in itinerant ferromagnet Sr${}_{1-x}$(La${}_{0.5}$K${}_{0.5}$)${}_x$RuO${}_3$

Abstract

We demonstrate that the cluster-glass state emerges as ferromagnetic quantum criticality is avoided in itinerant ferromagnet Sr1-x(La0.5K0.5)xRuO3. In this compound, the ferromagnetic order is suppressed by increasing x, and then disappears at the critical concentration: x=0.5. In this x range, the present study reveals that no prominent feature is ascribed to the quantum critical fluctuations in specific heat. Instead, ac magnetic susceptibility exhibits a broad peak due to spontaneous spin freezing, and the peak temperature depends significantly on the frequency of the applied ac magnetic field. Furthermore, specific heat is enhanced within a wide temperature range, whereas specific heat shows no salient anomaly associated with spin freezing. These features are characteristics of the formation of cluster-glass; in particular, the observed frequency variations in ac magnetic susceptibility are well described by the Vogel-Fulcher law. We compare the features concerning the suppression of the ferromagnetic order in this doped compound with those in isostructural Ca- and La-doped SrRuO3, and suggest that a local correlated disorder effect and the very small coherence of itinerant Ru 4d electrons are responsible for the cluster-glass formation instead of the quantum phase transition in Sr1-x(La0.5K0.5)xRuO3.

9 pages, 7 figures, to appear in Phys. Rev. Materials

References in corpus (5)

• Quantum Griffiths effects and smeared phase transitions in metals: theory and experiment
• Quasiparticle Mass Enhancement and Temperature Dependence of the Electronic Structure of Ferromagnetic SrRuO3 Thin Films
• Structural and physical properties of $SrM{n}_{1-x}R{u}_x{O}_3$ perovskites
• Antiferromagnetic Order in Disorder-Induced Insulating Phase of SrRu_{1-x}Mn_xO_3 (0.4<x<0.6)
• Correlation effect in Sr${}_{1-x}$La${}_x$RuO${}_3$ studied by soft x-ray photoemission spectroscopy