T

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Yashima et al., unpublished.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)