perconductivity and non-Fermi-liqui behavior of Ce 2 PdIn 8 V. H. Tran et al., PHYSICAL REVIEW B 83, 064504 (2011) Kitaoka Lab. M1 Ryuji Michizoe
Superconductivity and non-Fermi-liquid behavior of Ce2PdIn8
V. H. Tran et al., PHYSICAL REVIEW B 83, 064504 (2011)
Kitaoka Lab. M1
Ryuji Michizoe
Contents・ Introduction
- History of Superconductivity
- Heavy fermion system
・ Results
・ Summary
under high pressure
0
50
100
150
200
SmO0.9F0.11FeAs
LaO0.89F0.11FeAs
LaOFeP
Hg-Ba-Ca-Cu-O( )
Hg-Ba-Ca-Cu-O
Tl-Ba-Ca-Cu-O
Bi-Sr-Ca-Cu-O
Y-Ba-Cu-O
MgB2
NbGe
NbNNbC
NbPb
high-Tc cuprate
metal
iron-based system
SC
tra
nsi
tion t
em
pera
ture
-Tc
(K)
1900 1920 1940 1960 1980 2000 2020
Year
Hg
La-Ba-Cu-O
Discovery of superconducting phenomenon
1911
1986
High-Tc cuprate superconductor
2006
Iron-based high-Tc superconductor
77
163
History of Superconductivity(SC)
1979
Heavy fermion superconductor
CeCu2Si2
heavy fermion system
PuCoGa5
UPt3 UPd2Al3
CeCu2Si2 CePd2Si2 CeRh2Si2 CeIn3 CeRhIn5
PrOs4Sb12PuCoGa5 etcf electrons
Heavy fermion compounds
n(r)
r
4f5p
5d6s
+ +f f+f
+ +f f
+f
Heavy fermion stateNormal metal
+ ++
+ ++
Heavy fermion state
c-f hybridization
conduction electron
JcfJcf
Polarization
The interplay between two 4f electrons mediated by conduction electrons
Heavy fermion systemRKKY interaction
Conduction electron
4f electron
Magnetic Order
Heavy fermion system
4f and conduction electrons form a spin-singlet state
Kondo effect
Jcf
Conduction electron
4f electron
Fermi Liquid
TK W exp(-1/∝ J cf D(εF))
TRKKY D(ε∝ F) Jcf2
Phase Diagram of HF system
AFM : antiferromagnetismHF : heavy fermion stateQCP : quantum critical point
Kondo effect
4f electron
Kondo effect
Conduction electron
P dependence of Tmax
Above Tmax
Incoherent Kondo scattering
Below Tmax
Coherent Kondo scattering
Tmax shifts to high T
P dependence of Tmax
Tmax ∝ TK
Resistivity of Ce2PdIn8
P decreases Tc
1 barTc
~ 0.7 K
The P dependence of TC
P suppresses SC
P ~ 21 kbar
SC disappears
Non-Fermi-liquid behaviorFermi-liquid
ρ(T ) = ρ0 + AT 2
ρ(T ) = ρ0 + AT n (n < 2)
n = 1 : 2D antiferromagnetic spin fluctuationn = 1.5 : 3D antiferromagnetic spin fluctuationn = 2 : Fermi-liquid
Non-Fermi-liquid
P dependent values of n , A , ρ0ρ(T ) = ρ0 + AT n
n = 1 : 2D antiferromagnetic spin fluctuationn = 1.5 : 3D antiferromagnetic spin fluctuationn = 2 : Fermi-liquid
A T∝ K-2
P dependent values of n , A , ρ0ρ(T ) = ρ0 + AT n
n = 1 : 2D antiferromagnetic spin fluctuationn = 1.5 : 3D antiferromagnetic spin fluctuationn = 2 : Fermi-liquid
AF spin fluctuation is supressed by increasing P
V. A. Sidorov et al., PRL 89.157004 (2002)
SC may be associated with AF spin fluctuation
The relationship between SC and AF spin fluctuation
non-Fermi-liquid
Fermi-liquid
TFL : Fermi-liquid temperature
Field dependence of resistivityBelow Hc2 = 2.5 Tρ(T ) ∝ AT
Above Hc2 = 2.5 Tρ(T ) ∝ AT 2
n = 1 : 2D antiferromagnetic spin fluctuationn = 1.5 : 3D antiferromagnetic spin fluctuationn = 2 : Fermi-liquid
TFL increases with rising field
Fermi-liquid is recovered at strong magnetic fields
Field dependence of resistivity
Field dependent values of n , A , ρ0
near Hc2
n : jump to n = 2
A : maximum
ρ0 : minimum
AF spin fluctuationsassociated with a QCP
Fermi-liquid
ρ(T ) = ρ0 + AT n Hc2
n = 1 : 2D antiferromagnetic spin fluctuationn = 1.5 : 3D antiferromagnetic spin fluctuationn = 2 : Fermi-liquid
SummaryHc2
n = 1 : 2D antiferromagnetic spin fluctuationn = 1.5 : 3D antiferromagnetic spin fluctuationn = 2 : Fermi-liquid
SC in Ce2PdIn8 may be mediated by the AF spin fluctuations
END
H. Fukazawa et al., PHYSICAL REVIEW B 86, 094508 (2012)
Ce2PdIn8
Heavy fermion system
(RKKY:Rudermann-Kittel-Kasuya-Yoshida)
Magnetic Order Fermi Liquid
Conduction electron
4f electron
RKKY interaction
The interplay between two 4f electrons mediated by conduction electrons
4f electron
Kondo effect
4f and conduction electrons form a spin-singlet state.
Conduction electron
heavy fermion system : 重い電子系
field dependence of the resistivity
at 1 bar
μ0H < 3 T
Tmax no change⇒
μ0H > 3 T
Tmax toward lower temperature⇒
suppress spin fluctuation
Kondo interaction strength(CK)
CK decreases with P
Ck : Kondo interaction strength
Ck : Kondo interaction strength
CK ~ J3N(EF)2
J : hybridizationN(EF) : density of states at Fermi level
P enhances J
N(EF) strongly diminishes
CK decreases
P dependence of CK
CK decreases with P
but