orbital loopcurrent electronic nematic 300 Strange Metal 200
量子臨界点の存在？: 競合・共存する多種の秩序 orbital loop-current ( 軌道ループ電流秩序) electronic nematic 300 ( ネマテック電子秩序) Strange Metal （奇妙な金属） 200 擬ギャップ） T* TN TSCon TCDWon 温度 T (K) Pseudogap（ 100 AF 0 スピン秩序 spin order 電荷秩序 charge order TSDWon 0. 1 Tc 正常金属 （フ ェルミ液体） d-SC FL d波超伝導 0. 2 正孔ドーピング量 Hole doping p B. Keimer, S. A. Kivelson, M. R. Norman, S. Uchida, J. Zaanen, Nature 518, 179 (2015). 10
強磁場下の相図: 電荷・スピンの長距離秩序 300 Strange Metal 200 擬ギャップ） TN T* TSCon TCDWon 温度 T (K) Pseudogap（ （奇妙な金属） 100 AF 電子の結晶化 スピン秩序 spin order TSDW 0 電荷秩序 charge order TS onset 0. 1 Tc TCDW d-SC 正常金属 （フ ェルミ液体） FL d波超伝導 0. 2 正孔ドーピング量 Hole doping p B. Keimer, S. A. Kivelson, M. R. Norman, S. Uchida, J. Zaanen, Nature 518, 179 (2015). 11
フェルミ面のトポロジー変化 La 2 -x. Srx. Cu. O 4 (LSCO) at x = 0. 22: QCP ? Ortho-Tetra構造転移？ T. Yoshida, A. Fujimori et al. , Phys. Rev. 518, 179 (2015). 12 13
擬ギャップ相：粒子性（コヒーレンス）の部分回復 擬ギャップ相： ノード近傍で粒子性が部分的に回復 。 S. I. Mirzaei, M. R. Greven, D. van der Marel et al. , PNAS 110, 5774 (2013). N. Barisic, M. Dressel, M. R. Greven et al. , PNAS 110, 12235 (2013). 29
Supplementary Informations 33
量子臨界領域の普遍的性質 Thermal equilibrium time tp, the time it takes for the system to relax back to local thermal equilibrium after it is disturbed by an arbitrary external perturbation. QC region is distinguished by its ability to relax to thermal equilibrium in the shortest possible time: tp = Ceq ħ/k. BT The time is the shortest allowed by quantum mechanics: DE Dt ≥ ħ ; DE ~ k. BT → Dt ~ t ≥ ħ/k. BT QC fluid is a nearly perfect fluid with minimal shear viscocity h. h/s = Cm ħ/k. B (≥ħ/4 p k. B) h = e(T)t(T), s ~ nk. B, e ~ nk. BT → t(T) ~ ħ/4 pk. BT → r ~ T Charge transport originating from proximity to a QCP is inherently hydrodynamic. J. D. Rameau, P. D. Johnson et al. , Phys. Rev. B 90, 134509 (2014). 34
Temperature T (K) Pure d-Wave SC in the OD Regime ? 200 PG 100 SC fluctuations 0 superfluid phase separated ? Tc AF 0 T* Fermi liquid d-SC 0. 2 0. 1 Hole doping p 0. 3 Y. J. Uemura, Solid State Commun. 120, 347 (2001). Y. J. Uemura, J. Phys. : Condens. QCP ? Matter 16, S 4515 (2004). 35
Anomalous Overdoped Regime: Superfluid Density “The superfluid density decreases, while the normal-state carrier density increases” Y. J. Uemura et al. , Nature 364, 605 (1993). C. Bernhard et al. , Phys. Rev. Lett. 77, 2304 (1996). 35 36
Anomalous Overdoped Regime: Superfluid Density “Superconducting electrons go missing” J. Zaanen, Nature 536, 282 (2016). I. Bozovic et al. , Nature 536, 309 (2016). 36 37
Anomalous Overdoped Regime: Large Residual Conductivity and Absence of Josephson Plasma YBa 2 Cu 3 O 7 T. Pham et al, PRB 44, 5377 (1991). A. V. Puchkov, T. Timusk et al. , PRB 51, 3312 (1995). S. Uchida, K. Tamasaku, and S. Tajima, PRB 53, 14558 (1996). 37 38
Anomalous Overdoped Regime: Upper Critical Field A. P. Mackenzie et al. , PRL 71, 1238 (1993). 38 39
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