Superconductivity and non-Fermi-liquid 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