Tuning quantum critical points by impurity scattering seen via specific heat measurements

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K17692
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics II
• Research Institution: The University of Tokyo
• Principal Investigator: Mizukami Yuta 東京大学, 大学院新領域創成科学研究科, 助教 (80734095)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 鉄系超伝導 / 重い電子系超伝導 / 反強磁性秩序 / 電子ネマティック秩序 / 量子臨界点 / 精密比熱測定 / 電子線照射 / 元素置換効果

Outline of Final Research Achievements

In strongly correlated electron system, anomalous physical properties and exotic superconductivity often emerge near the quantum critical point(QCP) of ordered phase such as magnetic order, orbital order, and charge order. By using electron irradiation, we have observed synchronized shifts of magnetic QCP and high-temperature superconducting phase in iron-pnictide superconductors, suggesting the QCP may enhance superconductivity. In heavy-fermion superconductor CeCu2Si2, a prototypical superconductor which emerges near the magnetic QCP, we have suggested exotic mechanism through the systematic study using electron irradiation. In iron-chalcogenide FeSe, we have suppressed the orbital order by S substitution. Our studies have revealed that the superconducting state abruptly changes across the orbital QCP.

Free Research Field

超伝導、磁性