Institute of Materials Structure Science Symposium 2008

17th, Octorber 2008, Tsukuba

Advance in structural materials science
using synchrotron light, neutron, and muon

Comments- High-Tc superconductivity Discussion Leader
Jun Akimitsu
Department of Physics and Mathematics,
Aoyama Gakuin University
Akimitsu Lab. HP
URL http://www.phys.aoyama.ac.jp/~w3-jun/

High Tc Superconductivity
z Spatial Correlation in the Vortex Matter Systems

Steve Leez Challenging Experiments for Cuprate
Superconductors
Kazuyoshi Yamadaz Angle-resolved Photoemission Spectroscopy ofHigh-Tc Superconductors: Present Status andOutlookAtsushi Fujimori

Introduction

 Most attractive word in the Physics Society is“Deep”
 On the other hand, in the Chemistry Society is“New”“Deep Physics” through “New Material”
Aoyama-Gakuin
University

Triangle Phase Diagram
Magnetism

Coexistence between Magnetism
and Superconductivity

Superconductivity

Multiferroics
Chirality & DM interaction

From Bond to Band

Polarizability

From Real Space Pairing to
Reciprocal Lattice Pairing

Aoyama-Gakuin
University

Phase Diagram

Magnetism

Multiferroics
Chirality & DM interaction

Polarizability

Aoyama-Gakuin
University

Chiral Helimagnetism
Symmetric helixNo difference
between righthanded and left
handed screws

Dy, Ho(Ferro)chiral helix  (Antiferro)chiral helix
Only right- (or left-)  Alternating right-handed
and left-handed screws
handed screws

MnSi, CsCuCl3 (?)

CuB2O4 (?)
Aoyama-Gakuin
University

Chirality of CsCuCl3
 Determination of Crystallographic and Magnetic

Chirality in CsCuCl3
Resonant Circularly-polarized X-ray Diffraction
 Non-resonant Circularly-polarized X-ray Diffraction(Left-handed: P6122)(Right-handed: P6522)
Aoyama-Gakuin
University

Resonat Circularly-polarized X-ray Diffraction
 Experimantal (@ BL19LXU, SPring-8)

Energy: 8.996 keV (Cu2+ K-edge)
 T = Room temperatureSample with SG: P6122 and P6522


Crystallographic chirality wasdetermined by X-ray oscillation
photograph

0.1 mmAoyama-Gakuin
University

Resonat Circularly-polarized X-ray Diffraction
 Reciprocal lattice scan with P6122 sample

Intensity [arb. units]

0.006

10

Right-handed circularlypolarized light
Left-handed circularlypolarized light8
Intensity [arb. units]

0.007(0,0,12)

0.005
0.004
0.003
0.002
0.001
0
-0.015 -0.01 -0.005 0 0.005 0.01 0.015(0, 0, 10+δ)(0,0,14)
0.006

Right-handed circularlypolarized light
Left-handed circularlypolarized light6
4
2
0-0.015 -0.01 -0.005 0 0.005 0.01 0.015(0, 0, 12+δ)

0.005
Intensity [arb. units](0,0,10)

Right-handed circularlypolarized light
Left-handed circularlypolarized light

0.004
0.003
0.002
0.001
0
-0.015 -0.01 -0.005 0 0.005 0.01 0.015(0, 0, 14+δ)Intensities in (0,0,6n±2) are flipped by thechange of circular polarization
Aoyama-Gakuin
University

Resonat Circularly-polarized X-ray Diffraction
 Reciprocal lattice scan with P6522 sample

Intensity [arb. units]

0.004

Right-handed circularlypolarized light
Left-handed circularlypolarized lightIntensity [arb. units]

0.005(0,0,12)

0.003
0.002
0.001
0
-0.015 -0.01 -0.005 0 0.005 0.01 0.015(0, 0, 10+δ)20(0,0,14)0.005

Right-handed circularlypolarized light
Left-handed circularlypolarized light

15

10

5

0
-0.02-0.015-0.01-0.005 0 0.005 0.01 0.015(0, 0, 12+δ)

0.004
Intensity [arb. units](0,0,10)

Right-handed circularlypolarized light
Left-handed circularlypolarized light

0.003
0.002
0.001
0
-0.015 -0.01 -0.005 0 0.005 0.01 0.015(0, 0, 14+δ)Intensities in (0,0,6n±2) are flipped by thechange of crystallographic chirality
Aoyama-Gakuin
University

Phase Diagram

Superconductivity

Coexistence between Magnetism
and Superconductivity

Magnetism

Aoyama-Gakuin
University

Coexistence between superconductivity and magnetism
Hg-1245 system(Tc=108K; 5-CuO2 plane)

By Kitaoka group

Aoyama-Gakuin
University

Coexistence between superconductivity and magnetism
R

Tm5Rh6Sn18

SnRh

Single crystal
111

c = 27.4Å

100=(Sn1-xRx)a

By Naoki Kase (DC2)

13

.7
Å

Crystal size; 3×3×5mm

Aoyama-Gakuin
University

Coexistence between superconductivity and magnetism
Resistivity under magnetic fields and H-T phase diagram in Tm5Rh6Sn18

MO

SC“Reentrant superconductivity” was observed at low temperature.
Aoyama-Gakuin
University

0.12

Fitting function

Asy 1
Asy 2
A

0.1

A1exp(-λ1t)cos(f t + δ) + A2exp(-λ2t) + AB

B

0.08
0.06

A1/(A1 + A2) = 0.67

0.04

Magnetic Volume Function is ~100 %

0.02
0
2.5
f ( MHz )Corrected AsymmetrymSR measurement

f = f(0)(1 - T/Tm)β2
1.5Internal magnetic field, H = 170 Oe

1
0.5

T
Tm Rh Sn500.1

f = γH6

Tm = 6.7 K
c

18

1
T(K)

Tm 10

Tm is corresponding to TM obtained
from specific heat measurement.
Aoyama-Gakuin
University

Superconductivity in (Y,Tm)5Rh6Sn18
Y-Tm-Rh-Sn

3.2
3

-0.2
Y-6%
Y-14%
Y-32%
Y-40%
Y-48%
Y-72%

-0.4
-0.6

2

2.5

3

T (K)

3.5

4

4.5

Tc ( K )

0

-0.8
1.5



3.4

H // 100
H = 10 Oe-2

χ ( 10 emu/g )0.2

Y-Tm-Rh-Sn

2.8
2.6
2.4
2.2
2

0

20

40

60

Y contents ( % )

80

100

Tc is changed by Y-doping to Tm site.

Aoyama-Gakuin
University

H-T phase diagramsof (Y,Tm)5Rh6Sn18

H ( kOe )H // 100

MO

3
TM

2

0
4

Y-14%

TM

2
SC

Y-20%

H ( kOe )

4

Tc

SC

2

3

H // 100

TM

2
Tc

SC

1

T?

T?

MO

8
6

??
Tc

4

MO

H // 100MO

30

H // 100

??
Tc

1

Y-32%

T?

SC

1

H ( kOe )By Y-doping The region of SC is enlarged.
 Reentrant SC state isdisappeared at 32% doping.

H ( kOe )



Y-6%

4

T?
??

0

0

0.5

1

1.5

2

T( K )

2.5

3

3.5

0

0

0.5

1

1.5
2
T ( K )

2.5

3

3.5

Aoyama-Gakuin
University

Phase Diagram

Superconductivity

From Bond to Band

Polarizability

From Real Space Pairing to
Reciprocal Lattice Pairing

Aoyama-Gakuin
University

From bond to band (by H. Fukuyama)
Superconductivity in B-doped diamond, SiC and MgB2.

Mg

Carrier-doping

Carrier-doping

Carrier-doping

B
B
Si
C

MgB2

C

Diamond

SiC

Covalent bonds become bands by carrier-doping.
Aoyama-Gakuin
University

Superconductivity in B-doped SiC


Tc~1.4K


Hole carrier

ΔTc: 0.15K
1.06-1.91×1021 cm-3
B-substitution is 2.2-3.9 at%

Z.-A. Ren

T. Muranaka

Type-I SC stateNo T-hysteresis was observed
under zero field.
The degree of T-hysteresis wasenhanced with decreasing
temperature.
Hc=115Oe(S→N),
HSC=85Oe(N→S)

Z.-A. Ren et al., JPSJ 76(10), 103710 (2007).

Aoyama-Gakuin
University

Crystal structure of Ag6O8MX
The silver-oxide Ag6O8MX (M = cation, X = anion) has a clathrate-type
structure which consists of face sharing Ag6O8 cage containing anion (X-)
at its center.
Crystal system: Cubic
Space group: Fm3m

O
K. Kawashima
・Ag6O8AgNO3 (Tc=1.04 K)
・Ag6O8AgBF4 (Tc=0.35 K)
・Ag6O8AgHF2 (Tc=0.15~1.5 K)
・Ag6O8AgHSO4Ag(II, III)cation(M+)
anion (X-)

・Ag6O8AgHCO3
・Ag6O8AgClO4[1] J. Selbin et al., J. Inorg. Nucl. Chem., 20 (1961) 91.
[2] M. B. Robin et al., Phys. Rev. Lett. 17 (1966) 917.
[3] M. Jansen et al., J. Alloys and Compounds 183 (1992) 45.

Aoyama-Gakuin
University

Normal state of Ag6O8AgNO3 and Ag6O8AgHF2
Ag6O8AgNO3

Ag6O8AgNO3

700

I = 1.0 mA

300

Resistivity ( μΩcm )180 K: Structural phase-transition
from Cubic to Tetragonal.

Resistivity [ μΩcm ]Ag6O8AgNO3 shows phasetransitions near 90 K and 180 K.

350

Ag6O8AgHF2

250
200
150
100
50

-7
Susceptibility [ 10 emu/g ] Heat capacity: C ( J/mol・K )0

Small phase transition:
stopping of NO3- ions rotation?

400
300
200
100
0
3.0
H = 50000 G-7

Ag6O8AgHF2

Susceptibility [ 10 emu/g ]90 K:

C [ J/mol・K ](We confirmed this transition using X-ray diffraction).

Ag6O8AgHF2 shows phase transition
near 110 K. We consider that thistransition is generated by stop of
HF2- ions spin like Ag6O8AgNO3material.

2.5
2.0
1.5
1.0

0

50

100

150

200

Temperature [ K ]

250

300

600
500
400
300
200
100
0
400
300
200
100
0

8
H = 50000 G

7
6
5
4
3
2

0

50

100

150

200

250

300

Temperature [ K ]Aoyama-Gakuin
University

Superconducting state of Ag6O8AgNO3 and Ag6O8AgHF2
Ag6O8AgNO3
Ag6O8AgNO3 shows superconducting transition at 1.04 K as described in a previous report. We
determine a upper critical field: Hc2 to be 770 Oe and calculated coherence length: ζ to be 42.5
nm.
Resistivity & heat capacity.

ac-susceptibility.

0.6

I = 1.0 mA

H=0G
50 G
100 G
150 G
200 G
250 G
300 G
400 G

H c2 ( G )Specific heat: C ( mJ/mol・K )Resistivity [ μΩcm ]

1.0
0.8

0.4
0.2
0
100
80

Heat capacity
Resistivity
ac-susceptibility ( H sweep )ac-susceptibility ( T sweep )800

H = 0 Oe
50 G
100 G
150 G
200 G
250 G

600

400

200

60
40

0
0

20
Ag O AgNO
6

0
0.4

0.5

0.6

0.7

0.8

0.9

8

1

1.1

0.2

0.4

0.6

0.8

1

T (K)

3

1.2

c

Temperature ( K )Ag6O8AgHF2
We confirmed superconducting transition at 1.5 K more clear than previous report andperformed some measurements to elucidate superconducting state in Ag6O8AgHF2.
Aoyama-Gakuin
University

Conclusion
Magnetism

Coexistence between Magnetism
and Superconductivity

Superconductivity

Multiferroics
Chirality & DM interaction

From Bond to Band

Polarizability

From Real Space Pairing to
Reciprocal Lattice Pairing

Aoyama-Gakuin
University

Conclusion
Magnetism

ZnCr2Se4
CsCuCl3, CuB2O4

High-Tc Cuprate
Tm5Rh6Sn18

Superconductivity

MgB2 , B-doped SiC

Polarizability

B-doped SiC

Aoyama-Gakuin
University

Aoyama-Gakuin
University

Multiferroics

Magnetic Field

Magnetization

Electric Field

Polarization

ZnCr2Se4


Controling magnetic chiral domains with electric polarization

Polarized Neutron Diffraction

Inverse DM Interaction

P ∝ Q × ( Si × Si +1 )P

Akimitsu & Siratori

Katsura et al.
Aoyama-Gakuin
University

Chirality & DM Interaction
Symmetric Helix(Ferro)chiral Helix

No difference Only right (or left)
between right-handed
handed screw
and left handed screw

Dy, HoCsCuCl3(Antiferro)chiral Helix

Alternating righthanded and lefthanded screw

CuB2O4
Aoyama-Gakuin
University

Observation of Chirality
 Collaborators

Y. Kousaka, Y. Nakao, E. Kaya (Aoyama-Gakuin
University) S. Sakai (Hiroshima University) H. Ohsumi, T. Komesu (RIKEN) T. Arima (Tohoku University)


Aoyama-Gakuin
University

What is “Chirality” ?
 "I call any geometrical figure, or group of

points, chiral, and say it has chirality, if its
image in a plane mirror, ideally realized,
cannot be brought to coincide with itself.“
Lord Kelvin (1904)

Plane mirror
Aoyama-Gakuin
University

How to Observe Chiral Helimagnetism


Polarized Neutron Diffraction Experiments
Magnetic scattering cross section

{

}

⎧Q
2
⎡
⎤
(
)
(
)(
)
(
)
1
2
δ
+
⋅
+
⋅
⋅
=
−
Q
q
Q
q
P
Q
Q
K
q
2
⎛ dσ ⎞⎪⎟ = AS ⎢⎜⎥⎨ q : Magnetic propagation vector2⎝ dΩ ⎠⎢⎣+ 1 + (Q ⋅ q ) − 2(Q ⋅ q )(P ⋅ Q ) δ (Q = K + q )⎥⎦ ⎪ P : Neutron spin direction⎩{: Scattering vector}

M. Blume et al.


Neutron spin P is parallel to Q
2⎛ dσ ⎞⎟ = 4A S⎜⎝ dΩ ⎠⎛ dσ ⎞⎟=0⎜⎝ dΩ ⎠

at Q = K-q
Q

at Q = K+q
K-q

K+q

Neutron spin P is antiparallel to Q
⎛ dσ ⎞
⎟=0
⎜
d
Ω
⎠
⎝
2
⎛ dσ ⎞⎟ = 4A S⎜⎝ dΩ ⎠

at Q = K-q
Q

at Q = K+q
K-q

K+q
Aoyama-Gakuin
University

How to Observe Chiral Helimagnetism


Polarized Neutron Diffraction ExperimentsComparing magnetic satellite intensities between up-spin
neutron and down-spin neutron

ZnCr2Se4
 MnSi TbMnO3


ZnCr2Se4, K. Siratori and J. Akimitsu et al.: J. Phys. Soc. Jpn. 48 (1980) 1111.

MnSi, M. Ishida et al.: J. Phys. Soc. Jpn. 54 (1985) 2975.

Aoyama-Gakuin
University

Circularly-polarized X-ray Diffraction
 Circularly-polarized X-ray Diffraction

New method to observe crystallographic andmagnetic chirality

Crystallographic chirality can be determined by resonant
X-ray diffraction method.
Magnetic chirality can be also detemined by nonresonant magnetic X-ray diffraction method
Circularly-polarization cannot be destroyed by anapplied magnetic field

Aoyama-Gakuin
University

Circularly-polarized X-ray Diffraction
z // qAsymmetric Magnetic Satellites
kiPolarized Neutron Diffraction
2 ⎡(1 + P )δ (Q = K − q ) ⎤⎛ dσ ⎞⎜⎟ = AS ⎢
⎥
(
)
(
)
P
Q
K
q
+
−
=
+
1
δ
⎝ dΩ ⎠⎦⎣kfy
S = (S cos(q ⋅ rn + φ ), S sin (q ⋅ rn + φ ),0)x

Circularly-polarized X-ray Diffraction

2
⎡
{
(
)
}
1
sin
θ
sin
θ
cos
θ
δ (Q = K − q ) ⎤
+
P
σ
d
2
⎛
⎞
⎜
⎟ = A' S ⎢
⎥
2
d
Ω
⎝
⎠
⎣⎢+ {(1 − P sin θ )sin θ cos θ } δ (Q = K + q )⎦⎥H. Ohsumi et al.: unpublishedP = 1 (Up-spin or right-handed)P = -1 (Down-spin or left-handed)
Q

Q
K-q

K+q

K-q

K+q
Aoyama-Gakuin
University

Introduction

CsCuCl3
Chiral Crystal Structure(SG: P6122 or P6522)
 Helimagnetic Sturcutrealong the c-axis (T < 10.5 K)

μ=0.58 (1), pitch angle = 5°(K. Adachi et al.)Left-handed: P6122

Right-handed: P6522
Aoyama-Gakuin
University

How to Observe Crystallograhic Chirality
 Determination of Crystallographic Chirality
Intensities of Cu2+ K-edge in (0,0,6n±2) with SG: P6122
2⎛
2 sin 2α22
⎜ I = 9 1 + sin θ ( f // − f ⊥ )1 + sin 2 θ (1 ± sin θ )4⎜2⎜
2 sin 2α2
2
1 + sin 2 θ (1 m sin θ )⎜ I = 9 1 + sin θ ( f // − f ⊥ )
4
⎝



(

)

(

)

(l = 6n − 2)

(

)

(

)

(l = 6n + 2 )Intensities of Cu2+ K-edge in (0,0,6n±2) with SG: P6522
2⎛
2 sin 2α22
⎜ I = 9 1 + sin θ ( f // − f ⊥ )1 + sin 2 θ (1 m sin θ )4⎜2⎜
2 sin 2α2
2
1 + sin 2 θ (1 ± sin θ )⎜ I = 9 1 + sin θ ( f // − f ⊥ )
4
⎝

(

)

(

)

(l = 6n − 2 )

(

)

(

)

(l = 6n + 2 )Asymmetric peak intensities are flipped by circularlypolarization and crystallographic chirality
Aoyama-Gakuin
University

How to Observe Crystallograhic Chirality
 Determination of Crystallographic Chirality
Intensities of Cu2+ K-edge in (0,0,6n±2) with SG: P6122• Right-handed circular-polarization• Left-handed circular-polarization
QQ(0, 0, 6n-2)
(0, 0, 6n-2)(0, 0, 6n+2)(0, 0, 6n+2)

Intensities of Cu2+ K-edge in (0,0,6n±2) with SG: P6522• Right-handed circular-polarization• Left-handed circular-polarization

Q(0, 0, 6n-2)(0, 0, 6n+2)

Q(0, 0, 6n-2)(0, 0, 6n+2)

Asymmetric peak intensities are flipped by circularlypolarization and crystallographic chirality
Aoyama-Gakuin
University

Summary Resonant Circularly-polarized X-ray Diffraction

We succeeded in detecting crystallographic chirality
in CsCuCl3

Asymmetric peak intensities were detected between (0,0,6n2) and (0,0,6n+2)
Asymmetric peak intensities were flipped by the change ofcircularly polarization.
Asymmetric peak intensities were also flipped by the changeof crystallographic chirality.

Aoyama-Gakuin
University

Specific heat
γTm = 250 mJ/molTm K2
γY = 3.0 mJ/molY K2

The anomaly (TM) occurs
around 6 K.

The very large Sommerfeld coefficient γTm was observed.
Tm5Rh6Sn18 can be categorized as a “heavy fermion superconductor”.
Aoyama-Gakuin
University

mSR measurement 1@RIKEN RAL in U.K.

sample＊RIKEN RAL
muon factory port 2＊Pulse muon beam

Ag foil, 99.998%, thin0.1mm
Polycrystalline sample
Beam collimator,φ 25 mm
3He cryostat

ZF T < 0.3 K
LF H < 4.0 kOe
Aoyama-Gakuin
University

mSR measurement 2
Asymmetry (arb. units)

ZF-mSR

0.22

1.6 K ZF
0.20
Corrected Asymmetry

1.6 K
5K
10 K
20 K
40 K
70 K

0.18
0.16
0.14
0.12
0.10

0

1

2

3
4
5
Time ( μs )

6

7

8

0.08
0

0.5

1
Time ( μs )1.5

2A1exp(-λ1t)cos(f t + δ) + A2exp(-λ2t) + AB
＊No Gaussian shape was observed above Tm＊Below Tm = 6 K, development of a quasi-static local magnetic field is clearly inferred fromthe observation of spontaneous oscillation signal in the μSR spectra.
Aoyama-Gakuin
University

mSR measurement 4
0.25

LF-1.0 kOe
5 Oe
50 Oe
100 Oe300 Oe500 Oe1.0 kOe
2.0 kOe
4.0 kOe

Corrected Asymmetry

Asymmetry (arb. units)

LF - 2.5 K
0.2

0.15

0.1

Ag back ground
0

1

2

3
4
5
Time ( μs )

6

7

8

0.05
0

1

2

3
4
5
Time ( μs )

6

7

8

Corrected asymmetry didn’t recover under strong magnetic field (H > Hint).
＊Internal magnetic field, H = 170 Oe
Spin dynamics exists.
Detailed analysis of LF-μSR measurements is currently in progress.
Aoyama-Gakuin
University

Synthesis results of (Y,Tm)5Rh6Sn18◆ (Y,Tm)5Rh6Sn18 (analysis by EPMA)(YxTm1-x)5Rh6Sn18
Nominal (Y%)(YxTm1-x)5Rh6Sn18

0 (Tm5Rh6Sn18)

Y contents

質量濃度

(%)

(%)

ー

0

ー

10

(Y0.06Tm0.94)5.1Rh6Sn18.8

6100.044

20(Y0.14Tm0.86)4.9Rh6Sn18.6

14101.798

30(Y0.20Tm0.80)5.0Rh6Sn18.7

20100.32340(Y0.32Tm0.68)4.9Rh6Sn18.7

32

101.784

50(Y0.40Tm0.60)4.9Rh6Sn18.7

40100.145

60(Y0.48Tm0.52)4.9Rh6Sn18.6

48

99.60580(Y0.72Tm0.28)4.8Rh6Sn18.6

72

101.402100 (Y5Rh6Sn18)

ー

100

ー

Aoyama-Gakuin
University

Superconductivity in (Y,Tm)5Rh6Sn18
300

Y-Tm-Rh-Sn
Y-14, 40, 72 %

1200
1000
800
600
400

Y-14%
Y-40%
Y-72%

200
0



0

20

40
2

Y-Tm-Rh-Sn

250

60

2

T (K )

80

100

γ ( mJ / mol K 2 )C/T ( mJ / Tm-mol K 2 )

1400

200
150
100
50
0

0

20

40

60

Y contents ( % )

80

100

Heavy electron state in Tm5Rh6Sn18 is decreased by Ydoping.

Aoyama-Gakuin
University

Conclusion＊From specific heat measurements, the reentrant superconductor Tm5Rh6Sn18 canbe categorized as a “heavy fermion superconductor”.

＊The μSR measurement shows developmentof a quasi-static local magnetic field isclearly inferred from the observation of spontaneous oscillation signal in the μSR
spectra under zero external field, where the magnetism persists even below Tc.
Strongly suggesting coexistence of magnetism and superconductivity＊Corrected asymmetry didn’t recover under strong magnetic field (H > Hint), spin
dynamics exits.

Aoyama-Gakuin
University

Superconductivity in MgB2

120

T = 39 [K]

100

-0.01

Resistivity [ μΩ cm ]Susceptibility [ emu/g ]

0

F.C.

T = 39 [K]
c

-0.02

-0.03
Z.F.C.

c

80
60
40
20

-0.04

H = 10 Oe
0

10

20

30

40

Temperature [ K ]

50

60

0

0

50

100

150

200

250

300

Temperature [ K ]Aoyama-Gakuin
University

Superconductivity in B-doped diamond

1st report;
E.A. Ekimov et al., Nature 428, 542(2004)

B-doping to diamond by synthesis at 8-9GPa,
2500-2800K
Tc～4K , Hc2～3.5TType-II SC

Subsequent reports;
Y. Takano et al., APL 85, 2851(2004).


CVD single crystalline films



At same B-concentration : about
8.5x1021cm-3
 (111)

Tc onset = 11.5K

(100)


Tc onset = 6.3K

E. Bustarret et al. PRL 93, 237005(2004).
H. Umezawa et al., cond-mat/0503303

Aoyama-Gakuin
University

From real space pairing to reciprocal pairing
Strong electron-phonon coupling leads to the insulator
Critical temperature: Tc



Tc*
Metal

CDW-type
Insulator

Superconductivity0

λ*Electron-phonon coupling: λFrom Electro-Conductive Oxides, Tsuda, Nasu, Fujimori, Siratori

Aoyama-Gakuin
UniversityCDW（insulator）
Superconductivity
R(T)/R(300)

From real space pairing to reciprocal pairingBa1-xKxBiO3

1.0●Saito et al.

0.5

0
0

100

200

300

Temperature (K)BaPb1-xBixO3(K1-xBax)0.3MoO3

4.0

Tc (K)



Nb1-xTaxSe3

3.0

2.0



(Nb1-xTax)Se3

0

0

0.05

0.10

0.15

0.20

x

New superconductor was realized byweakening the electron-phonon interaction.

Aoyama-Gakuin
University

In a previous repot
ex. Ag6O8AgNO3
Ag6O8AgNO3 shows multi phase-transitions
with decreasing temperature.
Robin and co-workers suggested that thesetransitions were generated with the structuralphase transitions.

Ag6O8AgNO3 shows superconductivity at 1.04 K[4] M. B. Robin et al., Phys. Rev. Lett. 17 (1966) 917.
[5] M. M. Conway et al,. J. Phys. Chem. Sol. 31 (1970) 2673

Aoyama-Gakuin
UniversityPowder X-ray diffraction patterns of
Ag6O8AgX (X=NO3, HF2)

20

(531)
(600)
(620)

(133)

(422)

(331)
(420)

(400)

10

Ag6O8AgNO3

(222)

30

40

50

(531)
(600)
(620)

(422)
(133)

(220)

(331)
(420)

(440)

(400)

5

Single crystalline samples.

(440)

(222)

X-ray: CuKα

(220)

(100)
(200)

Ag6O8AgNO3

(100)
(200)

Intensity ( arb. units )Ag6O8AgHF2

Ag6O8AgHF２

(cm)

60

2θ ( degrees )We succeeded in synthesizing single crystalline samples of Ag6O8AgNO3
and Ag6O8AgHF2.
Aoyama-Gakuin
University

Aoyama-Gakuin
University