Competing ground states in transition metal oxides: Behavior of itinerant Sr1−xCaxRuO3 close to the classical and quantum critical ferromagnetic phase transition

D. Fuchs, C. L. Huang, J. Schmalian, M. Wissinger, S. Schuppler, K. Grube, H. V. Löhneysen

Research output: Contribution to journalReview articlepeer-review

5 Citations (Scopus)

Abstract

The ferromagnetic (FM) phase transition of the itinerant electron-system Sr1−xCaxRuO3 can be tuned by chemical composition resulting in a quantum critical point (QCP) at the critical concentration xc≈ 0.7. Applying epitaxial pressure at constant x leads to a reduction of the Curie temperature Tc which is found to be proportional to the shrinkage of the unit-cell volume Vuc, shifting xc to higher values for tensile strained films. Surprisingly, the tetragonal distortion seems to play here only a minor role. With increasing x the critical scaling of the order parameter shows unusual behavior. The magnetic critical exponents β, γ, and δ change systematically from typical mean-field values at x = 0 with increasing x towards β = 1, γ = 0.9 and δ = 1.6 at x = 0.7. The results are discussed with respect to a crossover from mean-field-like behavior at x = 0 to a line of fixed points that might emerge in the strong-disorder limit as the system approaches the QCP at or near xc. Magnetic inhomogeneities are indeed suggested by a nonvanishing magnetic moment at xc and the evidence of a Griffiths phase as well as glass-like behavior close to xc. Although spin fluctuations certainly play an important role around xc as proposed previously, our highly accurate data of the magnetization M(T,B) and specific heat C(T,B) for x = 0.7 suggest dynamic scaling with an unusual dynamic exponent z = 1.8, incompatible with standard spin-fluctuation theories at a ferromagnetic QCP.

Original languageEnglish
Article numberA008
Pages (from-to)1105-1126
Number of pages22
JournalEuropean Physical Journal: Special Topics
Volume224
Issue number6
DOIs
Publication statusPublished - 2015 Jul 1

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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