Ce115系及び関連物質の圧力相図、磁気揺らぎ、超伝導 Superconductivity in Ce115 systems -115In-NQR study under pressure- S. Kawasaki Graduate School of Engineering Science, Osaka University Collaborators NQR measurements M. Yashima, Y. Mugino, H.Kan, H. Mukuda, Y. Kitaoka (Osaka Univ.), T. Mito (Kobe Univ.), Y. Kawasaki (Tokushima Univ.), H. Kotegawa, G.-q. Zheng (Okayama Univ.), C. Thessieu (Easy lab. http://www.easy-lab.co.uk/ ), K. Ishida (Kyoto Univ.) High quality single crystals H. Shishido, S. Araki, R. Settai, Y. Ōnuki (Osaka Univ.), D. Aoki (Tohoku Univ.), Y. Haga (JAERI) Contents １．重い電子系超伝導体２．NQRで見たCeRhIn5の零磁場圧力相図３．NQRで見たCeIrIn5の零磁場圧力相図４．今後の展開とまとめ (5. NQRで見たCeIn3の零磁場圧力相図まとめ) 重い電子系超伝導磁性に近接及び共存するもの (a). Narrow superconducting phase CeRh2Si2, (R.Movshovich et al., 1996) CePd2Si2, (F.M.Grosche et al., 1996) CeIn3, (N.D.Mathur et al., 1998) (b). Wide superconducting phase CeCu2Ge2, (D.Jaccard et al., 1992) CeCu2Si2, (F.Thomas et al., 1993) CeRhIn5, (H.Hegger et al., 2000) ___________________________ 超伝導が単一で存在するもの (いずれも圧力下でTc上昇) CeIrIn5, (C. Petrovic et al., 2001) CeCoIn5, (C. Petrovic et al., 2001) S. Kawasaki et al., J. Phys. Soc. Jpn. 73, 1647 (2004). Y. Kitaoka et al., J. Phys. Soc. Jpn. 74, 186 (2005). それぞれの超伝導発現機構は？ PuCoGa5, (J. Sarrao et al., 2002 ) PuRhGa5, (F. Wastin et al., 2003) CeIn3 から Pu115へ H.Hegger et al., Phys. Rev. Lett. 84, 4986 (2000). Pc ~ 2 GPa, Tc ~ 2 K CeRhIn5 N. D. Mathur et al., Nature 394, 39 (1998). Temperature (K) 6 T NQR PG TN 4 ρ Tc AFM 2 NQR J. L. Sarrao et al., Nature 420, 297 (2002). Pc ~ 0 GPa, Tc ~ 18 K Tc SC Pc ~ 2.5 GPa, Tc ~ 0.2 K 0 0 1 2 3 4 5 Pressure (GPa) 6 7 最近のトピックスから CeCu2(Si0.9Ge0.1)2における二相超伝導の観測 H. Q. Yuan et al., Science 302, 2104 (2003). New Journal of Physics 6, 132 (2004). 超伝導発現機構×２？磁性との関係は？ 1. CeRhIn5の現状 CeRhIn5における反強磁性と超伝導の共存 CeRhIn5 NQR intensity (a.u.) 3 10 1.6 GPa CeRhIn 5 TN 4.2 K TN = 2.8K115 In-NQR P = 1.6 GPa 10 2 0.4 K MF 6.0 -1 1.6 GPa 1 / T1 (sec ) Tc 10 10 10 1 6.5 7.0 7.5 8.0 Frequnecy (MHz) 0 ~T ~T3 -1 10 -1 10 10 2 10 1 10 0 10 -1 10 -2 10 -3 10 -4 TN Tc 10 0 UPd2Al3 ~T3 -1 27 Al-NQR H. Tou et al. 10 0 10 10 1 1 10 2 10 Temperature (K) S.Kawasaki et al., PRL 91, 137001 (2003). 2 磁気揺らぎを媒介とした超伝導 1000 CeRhIn5 Tc 2.46GPa 10 1 50 -1 -1 1 / T1T (sec K ) -1 1 / T1 (sec ) 100 0.1 0.01 0.1 1 0 0 50 10 Temperature (K) Yashima et al., unpublished. 100 100 8 7 NQR Intensity (a.u.) CeRhIn5における反強磁性‐常磁性転移 2.1 GPa付近でAFM消失(no QCP) 3K 4.2 K 6 Intensity (a.u.) CeRhIn5 P = 1.6 GPa TN = 2.8 K Hint ~ 80 Oe CeRhIn5 2.03 GPa 2.4 K 5 2.1 K 4 2.0 K 3 1.6 K 2 1.0 K 1 0 4.5 2.4 K 0.4 K 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Frequency (MHz) 1.44 K M. Yashima et al., unpublished 1K 6.0 6.5 7.0 7.5 Frequency (MHz) 8.0 ＊P = 2.15 GPaでは磁性消失(１００％常磁性) P-T phase diagram for CeIn3 CeIn3 In-NQR Intensity (arb.units.) P = 2.37 GPa T = 80 mK (below T N, T C) AFM+PM 115 P = 2.43 GPa T = 100 mK (below T N, T C) AFM P = 2.59 GPa T = 50 mK (below T C) 8 S. Kawasaki et al., J. Phys. Soc. Jpn. 73, 1647 (2004). 9 10 11 Frequency (MHz) PM 12 P Recent topics H. Shishido et al., J. Phys. Soc. Jpn. 74,1103 (2005). 高圧下dHvA測定から、 P = 2.3 GPa 付近にQCPを示唆 T1でもNFL 一次相転移と量子臨界点? 2. CeIrIn5の超伝導 Clue to understand SC in 115 systems universally Introduction ~Phase diagram for CeRhIn5 & CeRh1-xIrxIn5~ CeRh1-xIrxIn5 CeRhIn5 CeRh1-xIrxIn5 CeRhIn5 TN = 3.8 K CeIrIn5 Tc = 0.4 K P. G. Pagliuso et al., PRB 64, 100503(R) (2001) Ir → Rh元素置換は化学的な負の圧力効果を示唆 M. Yashima et al. T. Muramatsu et al. Introduction ~Previous NQR study on CeRh1-xIrxIn5~ 500 1 / T1T (sec-1K-1) 400 x=0 x = 0.5 x = 1.0 TN CeRhIn5 300 Tc 200 100 G.-q.Zheng et al., PRB 70, 014511 (2004) 0 0.1 CeIrIn5 1 10 Temperature (K) x = 0.35~0.5 反強磁性と超伝導の共存 x = 1.0 → 0.5 1 / T1Tの増大→Tcの上昇 SC1 は磁気ゆらぎを媒介とした超伝導を示唆 100 Introduction ~Superconductivity in CeIrIn5 under pressure~ 4 CeIrIn5 CeIrIn5 ambient P 1.0 GPa 1.58 GPa 2.1 GPa Tc 100 Resistivity [Muramatsu et al.] NQR [Present work] 10 -1 -1 1 / T1T (sec K ) Tempareture (K) 3 2 Tc P 1 1 115 In-NQR LaIrIn5 ambient P SC2 0 0.1 0 1 2 3 4 5 6 Pressure (GPa) 0.1 1 10 100 Temperature (K) S. Kawasaki et al., PRL 94, 037007 (2005). CeIrIn5 (x =1.0) P → 2.1 GPa Tc 上昇 (Tc = 0.8K) 常伝導状態 P > 1 GPa フェルミ液体状態 (1/T1T~const.）混晶系と比較すると115系にもTcを上昇させる機構が複数あるのは確からしい Experimental 元素置換によってTcが上昇するのはなぜか？ 115In-NQR P. G. Pagliuso et al., PRB 64, 100503(R) (2001) at x = 0.9 ~ 0.6. 115In I=9/2, 2νQ (±3/2⇔±5/2) Experimental results NQR スペクトル 1 Ir(Rh) T = 1.6 K T 1~4 msec x = 1.0 (T = 4.2 K) G.-q. Zheng et al. x = 0.9 (T = 0.2 K) 1-M(t)/M(0) Ce NQR Intensity (arb.units) In(1) x = 0.7 x = 0.8 (T = 0.2 K) 0.01 0.0 0.5 1.0 t (msec) 115 12 13 In-NQR, H = 0 14 Frequency (MHz) スペクトル→元素置換による線幅の増大緩和時間→電子状態は一様 1.5 CeRh 1-xIr xIn 5 x = 0.7 (T = 0.2 K) 11 0.1 15 Experimental result x dependence of 1 / T1T for CeRh1-xIrxIn5 CeRh1-xIrxIn5 1.5 200 CeRh 1-xIr xIn 5 x x x x -1 -1 1 / T1T (sec K ) 150 = = = = 1.0 Tc (K) Tc 0.7 0.8 0.9 1.0 x = 0.9 0.5 SC1 (G.-q. Zheng et al.) 100 0.0 0.6 0.7 0.8 0.9 1.0 X (Ir concentration) 50 x = 0.9 Tcの一時的減少(最小値) 0 0.1 1 Temperature (K) 10 100 x = 0.7 磁気揺らぎの急激な増大 →Tc 急上昇(Tc = 1.2 K) Preliminary result of x = 0.6 Tc CeRh1-xIrxIn5 ac-χ (a.u.) 1.5 Tc (K) 1.0 0.5 SC1 CeRh0.4Ir0.6In5 0.0 0.2 0.4 0.6 0.8 Temperature (K) 1.0 1.2 0.0 0.6 0.7 0.8 0.9 X (Ir concentration) Tcが x = 0.7で最大値をとることを確認 1.0 CeRh1-xIrxIn5の超伝導特性 115 1000 In-NQR H=0 ラインノードのギャップ関数 Tc 100 と、残留状態密度を仮定 -1 1 / T1 (sec ) 1/4 ~T 10 CeRh1-xIrxIn5 x = 0.7 x = 0.8 x = 0.9 x = 1.0 1 ~T [G.-q.Zheng et al.] 0.1 0.1 1 10 Temperature (K) 100 S. Schmitt-Rink et al., PRL 57, 2575 (1986) P. J. Hirschfeld et al., PRB 37, 83 (1988) 10 8 0.4 6 0.2 4 CeRh1-xIrxIn5 0.0 RDOS 2Δ0 / kBTc 0.6 SC1 は強結合超伝導 Tc は x = 0.7で最大値 Tc =1.2 Kをとる x = 0.9にSC1とSC2の相境界？ 1.5 (不純物濃度が最低⇔残留状態密度最大) Tc (K) 1.0 SC1 0.5 SC2 0.0 0.6 0.7 0.8 0.9 x (Ir concentration) 1.0 Tc最大の起源は何か？ CeIrIn5の常伝導状態の磁気揺らぎ SCR理論から、量子臨界点近傍において、 2D SFs anisotropic SFs 異方的な反強磁性スピン揺らぎのモデル 1 / T1T ∝ χQ3/4 (χQ∝1 / (T+θ)) C. Lacroix et al., PRB 54, 15178 (1996) H. Kondo JPSJ 71, 3011 (2002) 3D SFs cf) 二次元 1 / T1T ∝χQ 三次元 1 / T1T ∝χQ1/2 T. Moriya; Spin Fluctuations in Itinerant Electron Magnetism (Springer, Berlin, 1985) A. Ishigaki and T. Moriya JPSJ 67, 3924 (1998) For review see, T. Moriya and K. Ueda Adv. Phys. 49, 555 (2000) CeIrIn5 T1T ∝ (T+8)3/4 (θ=8 K) G-q. Zheng et al., PRL 86, 4664 (2001). CeRh1-xIrxIn5の量子臨界点と超伝導 0.14 10 anisotropic SFs 2D SFs CeRh1-xIrxIn5 1.5 0.12 T1T ~ T + 2 8 3/4 0.06 6 1.0 QCP 4 0.5 T1T ~ (T - 0.2) 0.04 1/2 2 3D SFs 0.02 0.0 CeRh0.3Ir0.7In5 0.6 0.7 0.8 0.9 1.0 X (Ir concentration) 0.00 0 20 40 60 80 100 120 Temperature (K) x ~ 0.7 に量子臨界点(QCP)が存在し、そこでTcは急激な上昇 →SC1は磁気揺らぎを媒介とした超伝導 0 θ (K) T1T ~ (T + 0.02) 0.08 Tc (K) T1T (secK) 0.10 Preliminary result 磁気揺らぎのｘ依存性 CeRh1-xIrxIn5 T* 115 In-NQR, H = 0 1000 ~T 1/2 -1 1 / T1 (sec ) Tc 100 x = 0.6 3/4 T1T ~ (T + θ ) x = 0.7 (θ = 0 K) x = 0.8 (θ = 2.7 K) x = 0.9 (θ = 4.9 K) x = 1.0 (θ = 8.0 K) 10 1 10 Temperature (K) 100 ここまでのまとめ ~二つの超伝導相と量子臨界点~ x = 0.7→量子臨界点 θ→ 0 Tcの急激な上昇(Tcmax = 1.2 K) 超伝導ギャップの増大 SC1は磁気揺らぎを媒介とした強結合超伝導 x = 0.9 →新たな臨界点orクロスオーバー？ Tc 最小(Tcmin = 0.35 K) 不純物濃度の低いx=0.9でRDOS発散。混晶系のまとめ Two superconducting phases and two criticalities exist in CeIrIn5 Pressure (GPa) 0 TN Temperature (K) 4 CeIrIn 5 zero Tc CeRh 1-xIr xIn 5 4 3 T. Muramatsu et al LANL This work 2 Tc 1 Tc SC1 0 0.0 6 Tc QCP 3 1 4 NQR AFM 2 2 0.5 SC2 1.0 0 x (Ir concentration) 他の115系との系統性はあるか(NQRの視点から)？ Existence of QCP is suggested in CeRhIn5 by dHvA measurement CeRhIn5 との共通点 dHvA measurement under P suggests the existence of QCP around 2.3 GPa Two criticalities in CeRhIn5? H. Shishido et al., J. Phys. Soc. Jpn. 74,1103 (2005). 磁気揺らぎの圧力(ｘ)依存性 CeRhIn5 under P CeRh1-xIrxIn5 CeRh1-xIrxIn5 T* 115 In-NQR, H = 0 1000 TN ∼T 1/2 1000 ~T 1/2 -1 1 / T1 (sec ) -1 1 / T1 (sec ) Tc TC T1T ~ (T+3.3) 3/4 CeRhIn5 x = 0.6 1.23GPa 2.03GPa 2.15GPa 2.35GPa 2.46GPa 100 100 3/4 T1T ~ (T + θ ) x = 0.7 (θ = 0 K) x = 0.8 (θ = 2.7 K) x = 0.9 (θ = 4.9 K) x = 1.0 (θ = 8.0 K) 10 TC 1 10 100 Temperature (K) 1 10 100 Temperature (K) M. Yashima et al., unpublished. ３次元→準２次元クロスオーバーは両系に共通して観測される。 CeRhIn5にも? Pc Tcmax with QCP? SC2はSCドーム内あるいはさらに高圧下に？(no data) ? Ce115系における超伝導発現機構(SC2: フェルミ液体状態でのTc上昇） CeIrIn5とCeCoIn5を比較して Tc 高い Tc 低い 10 -1 -1 1 / T1T (sec K ) CeIrIn5 ambient P 1.0 GPa 1.58 GPa 2.1 GPa Tc 100 P 1 115 In-NQR LaIrIn5 ambient P 0.1 0.1 1 10 100 Temperature (K) 混成効果がTcの上昇に寄与？ M. Yashima et al., JPSJ 73, 2073 (2004). NQRでまとめたCe115系の超伝導 Tc 高い Tc 低い CeIrIn5 CeRhIn5 CeCoIn5 1000 1000 115 In-NQR LaIrIn5 ambient P CeRhIn5 100 2.46GPa Tc -1 1 / T1 (sec ) 10 1 0.1 0.01 0.1 10 ~T 50 1 -1 -1 1 / T1T (sec K ) -1 1 / T1 (sec ) 100 1 0 0 50 100 10 ~T 0.1 3 100 CeIrIn5 ambient P 1.0 GPa 1.58 GPa 2.1 GPa Temperature (K) 0.1 1 10 100 Temperature(K) SC1 + SC2 mixed Compete? SC1 (Spin fluctuations) SC2 (Due to hybridization) 5. Pu115系超伝導 (Relative to Ce115?) Ce115系の超伝導を眺めた上でのコメント PuCoGa5 及び PuRhGa5の超伝導(最近のNQRの結果より) 1000 PuCoGa5 Ga(1)-NQR Tc ~T Tc低い Tc高い -1 1 / T1 (sec ) 100 10 0.4 -1 -1 T1T (sec K ) 0.6 1 0.2 T1T~(T+11) 0.0 1 0 50 10 3/4 100 150 200 100 Temperature (K) N. J. Curro et al., Nature 434, 622 (2005). LANL Tc = 18.5 K, γ～80 mJ/molK2 H. Sakai et al., JPSJ (2005). JAERI Tc ~ 8.5 K, γ~50-100 mJ/molK2 １１５系として統一理解出来うるか？ (Just my speculation) SC2 1000 1000 PuCoGa5 Ga(1)-NQR 115 In-NQR LaIrIn5 ambient P Tc ~T 100 -1 1 / T1 (sec ) Tc -1 1 / T1 (sec ) 100 10 0.6 ~T 1 -1 -1 T1T (sec K ) E.D.Bauer et al., PRL 93, 147005 (2004). 0.4 10 1 0.2 3/4 T1T~(T+11) 0.0 1 0 50 10 Temperature (K) SC1+SC2 ~T 0.1 100 150 200 3 CeIrIn5 ambient P 1.0 GPa 1.58 GPa 2.1 GPa 100 0.1 1 10 Temperature(K) 100 Summary 1st order? Pressure (GPa) 0 TN Temperature (K) 4 2 CeIrIn 5 SFs Tc CeRh 1-xIr xIn 5 QCP 1 LANL This work Fermi liquid Tc SC2 1.0 2 1 Tc 0.5 3 T. Muramatsu et al SC1 0 0.0 4 NQR zero 2 6 Tc AFM 3 4 0 x (Ir concentration) Future work(全て加圧) 超伝導発現機構としての SC1とSC2の存在は115系において確からしい。 Pressure-induced superconductivity in CeIn3 115In-NQR study under pressure (under zero magnetic field) 1. CeIn3の圧力誘起量子相転移 NQR spectrum Pressure-induced 1st-order magnetic phase transition Present work T. Muramatsu et al. [Resistivity] Temperature (K) 10 TN 2.17 GPa 2.28 GPa 5 AFM ρ 0 0.0 Tc 0.5 1.0 1.5 2.0 2.5 Pressure (GPa) 3.0 CeIn3 P = 2.17 GPa TN = 5.5 K Hint = 2.5 kOe NQR intensity (a.u.) 5.8 K 4.2 K 3.8 K NQR Intensity (a.u.) Antiferromagnetic order around Pc CeIn3 P = 2.28 GPa TN = 5.2 K Hint = 2 kOe PM PM+AFM 5.8 K 3.8 K 3K 3.5 K 2.5 K 1.5 K 1.4 K 19.0 19.5 20.0 20.5 Frequency (MHz) Homogeneous magnetic order 19.2 19.4 19.6 19.8 20.0 20.2 Frequency [MHz] Phase separation of AFM & PM →1st order phase transition Summary of static magnetic property in CeIn3 under pressure CeIn3 In-NQR Intensity (arb.units.) TN Pctricritical point AFM 5 2nd order 1st order 0 1.0 1.5 2.0 2.5 Pressure (GPa) PM 3.0 P = 2.43 GPa T = 100 mK (below T N, T C) AFM AFM+PM 115 Temperature (K) 10 P = 2.37 GPa T = 80 mK (below T N, T C) P = 2.59 GPa T = 50 mK (below T C) 8 9 10 11 Frequency (MHz) PM 12 P NQR intensity * T P-T magnetic phase diagram for CeIn3 1.0 0.5 2.43 GPa (reduce P) 2.47 GPa (apply P) 0.0 0 1 2 3 4 Temperature (K) CeIn3 NQR intensity (a.u.) P = 2.43 GPa (reduce P) P = 2.47 GPa (apply P) Hysteresis behavior against P is observed! T = 100 mK 7 8 9 10 11 12 Frequency (MHz) 13 14 2. CeIn3の電子状態と圧力誘起超伝導 NQR spin-lattice relaxation time Overview of P - T phase diagram of CeIn3 30 1000 T CeIn3 100 1 10 CeIn3 * 100 Temperature (K) Temperature (K) -1 1 / T1 (sec ) TN PM 20 Itinerant 10 -1 -1 1 / T1T (sec K ) ambient P 2.35 GPa 2.43 GPa 2.65 GPa TN 0 0.0 100 1 Pc TN AFM TFL 0 * Localized 300 200 T 10 Temperature (K) 100 0.5 1.0 1.5 2.0 2.5 Pressure (GPa) Fermi liquid 3.0 ・Below T* ,the system crosses over from the localized to itinerant magnetic regime. ･Above P > 2.43 GPa , below TFL, Fermiliquid state is established. (1/T1T ~const. behavior ) Trigger of 1st order magnetic phase transition 30 9.85 CeIn3 Temperature (K) Normal state νQ (MHz) 9.80 9.75 CeIn3 PM 20 * Localized Itinerant 10 TFL TN AFM 9.70 1.0 T 1.5 2.0 Pressure [GPa] 2.5 0 0.0 0.5 1.0 1.5 2.0 2.5 Pressure (GPa) Fermi liquid 3.0 Pressure-induced superconductivity in CeIn3 ac-susceptibility Tc 0 4πχac CeIn 3 2.17 2.28 2.37 2.43 2.50 2.65 -1 0.0 0.1 0.2 Temperature (K) 0.3 GPa GPa GPa GPa GPa GPa 0.4 Unconventional superconductivity 2.59 GPa 1000 CeIn3 115 In-NQR 2.59 GPa 100 10 1 ~T 3 NQR Intensity (a.u.) 1 / T1 ( sec -1 ) ~T T = 50mK 9 10 11 Frequency (MHz) 0.1 0.1 1 10 Temperature [K] 100 CeIn3 NQR intensity (a.u.) P = 2.47 GPa T = 100 mK Superconductivity in mixed phase 8 9 10 11 12 13 14 Frequency (MHz) 200 TcAFM -1 -1 1 / T1T (sec K ) 150 100 TcPM 50 P = 2.47 GPa (PM) P = 2.47 GPa (AFM) 0 0.1 RDOS is induced by the phase separation 1 Temperature [K] 10 100 Trigger of pressure-induced superconductivity 300 CeIn3 P = 2.17 GPa P = 2.28 GPa(PM) P = 2.28 GPa(AFM) AFM 200 TN -1 -1 1 / T1T (sec K ) TC 100 0 0.1 1 10 Temperature (K) Strong magnetic fluctuations even below TN is observed. 100 Summary of CeIn3 2nd-order to 1st-order phase transition around P = 2.2 GPa. CeIn3 has no QCP. Magnetic phase instability induced SC? 異常金属相 Additional magnetic fluctuations induces superconductivity in AFM. The highest Tc (=230mK) is observed in Fermi-liquid state at P = 2.43 GPa. 140 CeRh 0.2Ir0.8In 5 CeRh 0.1Ir0.9In 5 CeIrIn 5 CeRh 0.1Ir0.9In 5 (0.4 GPa) CeIrIn 5(1 GPa) 120 Tc -1 -1 1 / T1T (sec K ) 100 80 SC1 60 40 20 SC2 0 0.1 1 Temperature (K) 10 100 I=9/2, 2νQ (±3/2⇔±5/2) 1 1 12.458 MHz T = 1.6 K T1 ~ 4 msec T < Tc 1-M(t)/M(0) 1-M(t)/M(0) 12.21 MHz T = 0.06 K T1 ~ 900 msec 0.1 T > Tc 0.1 x = 0.9 0.01 0 50 x = 0.7 100 150 200 t (msec) 250 300 0.01 0.0 0.5 1.0 t (msec) 1.5 Pressure increases Tc in CeIrIn5 Chemical substitution acts as reducing P (replacing Ir with Rh) Applying pressure 115 In-NQR CeIrIn5 ambient P 1.0 GPa 1.58 GPa 2.1 GPa 500 Tc 50 TN LaIrIn5 ambient P -1 1 / T1T (sec K ) 300 -1 1 / T1T (sec-1K-1) 400 CeIrIn5 CeRh0.5Ir0.5In5 CeRhIn5 Tc 200 100 0 0 0.1 1 10 100 Temperature (K) G-q. Zheng et al., PRB 70, 014511 (2004) Magnetically mediated SC. 0.1 1 10 100 Temperature (K) S. Kawasaki et al., PRL 94, 037007 (2005). Another mechanism 115In-NQR study of CeIrIn5 under pressure 10 115 In-NQR -1 -1 1 / T1T (sec K ) 50 Tc 100 1 10 0.1 0.1 1 10 100 LaIrIn5 ambient P 0 0 50 Temperature (K) 100 0.1 -1 -1 1 T1 / T1 (Tc(P)) CeIrIn5 ambient P 1.0 GPa 1.58 GPa 2.1 GPa 0.01 0.1 115 CeIrIn5 In-NQR ambient P 1.0 GPa 1.58 GPa 2.1 GPa Δ0 = 2.5 kBTc 1 T / Tc(P) 115 ~T In-NQR H=0 ~T 1000 1/4 -1 1 / T1 (sec ) 1/2 CeRh1-xIrxIn5 x = 1.0 x = 0.9 x = 0.8 x = 0.7 x = 0.6 x=0 100 10 1 10 Temperature (K) 100 Tcにおける異常 CeRh1-xIrxIn5 [SC1]→ CeIrIn5 [SC2] 0.8 Tcχ ac-susceptibility (a.u.) χ Tc 0.6 0.4 1 RDOS x = 0.7 2 Tc (K) TcNQR NQR Tc 0.2 SC1 x = 0.8 0 0.6 SC2 0.8 0.0 1.0 x (Ir concentration) 0.0 0.2 0.4 0.6 0.8 1.0 Temperature (K) x = 0.9 x = 0.9でオンセットとバルクな Tcに最も大きな差が生じる。 1.2 SC1相とSC2相の競合に伴う相揺らぎ？ 1.4 Pressure dependence of c/a Pressure (GPa) 0 5 1.622 R. S. Kumar et al. PRB 70, 214526 (2004) 1.618 Ce c/a 1.616 Ir(Rh) 1.614 1.612 1.610 1.608 1.606 0.0 15 CeIrIn 5 1.620 In(1) 10 CeRh 1-xIr xIn 5 P. G. Pagisuso et al. PRB 64, 100503(R) (2001) 0.2 0.4 0.6 0.8 1.0 X (Ir concentration) c/a controls electric and magnetic properties in CeIrIn5 Summary of static magnetic properties CeIn3 4 NQR intensity * T 6 5 1.0 TN Hint (kOe) Temperature (K) 10 Hint 0.5 CeIn3 2.17 GPa 2.37 GPa 2.47 GPa 2.50 GPa 2 0 0 0.0 0.0 0.0 0 1 0.5 1.0 2 1.5 3 2.0 Pressure (GPa) 0.5 1.0 T / TN(P) 2.5 3.0 1.5 2.0 Pressure control 9.86 NQR intensity (a.u.) CeIn3 P = 2.59 GPa T = 4.2 K FWHM ~ 78 kHz 9.85 9.84 νQ (MHz) 9.83 9.4 9.6 9.8 10.0 Frequency (MHz) 10.2 9.82 CeIn3 9.81 reduce P apply P 10.4 9.80 9.79 9.78 10 kHz / 0.1 GPa 2.2 2.3 2.4 2.5 Pressure (GPa) 2.6 2.7 Experimental (Nuclear Quadrupole Resonance) ~Static magnetic property probed by NQR spectrum~ 1νQ Due to the internal field induced by the ordered moment, NQR spectrum should change its shape below TN. →PM signal should disappear below TN CeRhIn5の圧力誘起超伝導 CeRhIn5 1.12 GPa 1.53 GPa 1.6 GPa 1.75 GPa 1.9 GPa 2.0 GPa 0 1 2 CeRhIn5 6 P = 1.6 GPa NQR TPG 5 TN 3 (b) 4 1.5 MF dχac / d T Hint [kOe] Tc 7 3 AFM 1.0 2 SC 0.5 onset Tc 1 MF Tc 0.0 1.0 1.5 2.0 Pressure [GPa] 0 1 2 Temperature (K) 3 0 2.5 Temperature [K] χac (a.u.) (a)