## 摘要

The ferromagnetic (FM) phase transition of the itinerant electron-system Sr_{1−x}Ca_{x}RuO_{3} can be tuned by chemical composition resulting in a quantum critical point (QCP) at the critical concentration x_{c}≈ 0.7. Applying epitaxial pressure at constant x leads to a reduction of the Curie temperature T_{c} which is found to be proportional to the shrinkage of the unit-cell volume V_{uc}, shifting x_{c} 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 x_{c}. Magnetic inhomogeneities are indeed suggested by a nonvanishing magnetic moment at x_{c} and the evidence of a Griffiths phase as well as glass-like behavior close to x_{c}. Although spin fluctuations certainly play an important role around x_{c} 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.

原文 | English |
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文章編號 | A008 |

頁（從 - 到） | 1105-1126 |

頁數 | 22 |

期刊 | European Physical Journal: Special Topics |

卷 | 224 |

發行號 | 6 |

DOIs | |

出版狀態 | Published - 2015 7月 1 |

## All Science Journal Classification (ASJC) codes

- 材料科學(全部)
- 物理與天文學 (全部)
- 物理與理論化學

## 指紋

深入研究「Competing ground states in transition metal oxides: Behavior of itinerant Sr_{1−x}Ca

_{x}RuO

_{3}close to the classical and quantum critical ferromagnetic phase transition」主題。共同形成了獨特的指紋。