物性研短期研究会「遍歴系の特異な磁性と磁性材料への応用」 2004 年 5 月 13 － 15 日

物性研短期研究会「遍歴系の特異な磁性と磁性材料への応用」　 2004年 5月 13－ 15日

内殻内殻 MCDMCD から見た遍歴磁性体から見た遍歴磁性体

藤森　淳東大新領域、原研放射光

岡本　淳 , 間宮一敏，岡根哲夫，斉藤祐児 ,

吉井賢資，村松康司（原研放射光）

Ca1-xSrxRuO3 ， SrFe1-xCoxO3 ：高野幹夫、川崎修嗣（京大化研）

武田保雄（三重大工）

Co(S1-xSex)2 ：宮台朝直（道都大）

UGe2 ：芳賀芳範、山本悦嗣（原研先端研）

大貫惇陸（阪大理、原研先端研）

• 内殻吸収磁気円二色性（ Magnetic Circular Dichroism ： MCD ）– 得られる情報– SPring-8 原研ビームライン

• 研究例– 遍歴強磁性： Ca1-xSrxRuO3

– ヘリカル‐強磁性転移： SrFe1-xCoxO3

– メタ磁性： Co(S1-xSex)2

– 強磁性超伝導： UGe2

概要概要

A1 - A2

Magnetic circular dichroism (MCD) in core-level Magnetic circular dichroism (MCD) in core-level x-ray absorption (XAS) from metal x-ray absorption (XAS) from metal pp core level core level

site specific probe+

magnetic specific probe

spin sum rule

orbital sum rule

M p core

M d valence

h

First experiment of metal First experiment of metal pp core-level MCD: core-level MCD: Ni metalNi metal

C.T. Chen et al., PRB ‘90

+

-

+ -

MCD 装置

ARPES 装置

Low temperature down to 10 K

MCD endstation at JAERI beamline BL-23SU MCD endstation at JAERI beamline BL-23SU of Spring-8of Spring-8

“Hot” sample area

Superconducting magnet up to 10 T

• Magnetic semiconductors for spintronics　– Separation of ferromagnetic and paramagnetic

components

• Complex magnetic structure and transition• Metamagnetism• Uranium compounds

Scientific opportunities at the high-field, Scientific opportunities at the high-field, low-temperature MCD endstationlow-temperature MCD endstation

-150

-100

-50

0

50

100

150M

agne

tiza

tion

x10

-6 (

emu)

-20 -10 0 10 20

Magnetic Field (kG)

@5K @300K

Mtotal = Mferro + Mpara + Mdia (substrate)

Zn1-xCoxO thin film synthesized by pulsed laser deposition

M. Kobayashi, M. SaekiH. Tabata, and T. Kawai

MCD of ferromagnetic component

MCD of paramagnetic component

Separation of MCD into ferromagnetic and Separation of MCD into ferromagnetic and paramagnetic componentsparamagnetic components

• Magnetic semiconductors for spintronics　– Separation of ferromagnetic and paramagnetic

components

• Complex magnetic structure and transition• Metamagnetism• Uranium compounds

Scientific opportunities at the high-field, Scientific opportunities at the high-field, low-temperature MCD endstationlow-temperature MCD endstation






概要概要

TC

TC

TC

Sr

Ca

1.00.750.470.17

Itinerant-electron ferromagnetism in SrRuOItinerant-electron ferromagnetism in SrRuO33

and its suppression in Caand its suppression in Ca1-x1-xSrSrxxRuORuO33

F. Fukunaga and N. Tsuda, JPSJ ‘94

G. Cao et al., PRB ‘97

T. Kiyama et al., PRB ‘96

Magneto-volume effect

M-T curves Resistivity anomaly

0 0.2 0.4 0.6 0.8 1.0

150

100

50

0

T (K)

x

ferromagnetic

paramagnetic

Phase diagram

Ru 3Ru 3pp core-level MCD in Ca core-level MCD in Ca1-x1-xSrSrxxRuORuO33

J. Okamoto et al.

Background correction+/- light modulationMagnetization reversal --> extract MCD signal

500480460Photon Energy (eV)

Inte

nsi

ty (

arb

. un

its)

Ca1-xSrxRuO3

x = 0.3

x = 0

x = 0.4x = 0.5

x = 0.6x = 0.7x = 0.8x = 0.9x = 1

x = 0.3x = 0

x = 0.4x = 0.5x = 0.6x = 0.7x = 0.8

x = 0.9x = 1

MCD:

H = 2 TT =30 K

Ru M3 Ru M2


Okamoto, Yoshii et al.

-1.0

-0.5

0

0.5

1.0

-2 -1 0 1 2

Mag

net

izat

ion

( B

/Ru

ato

m)

Magnetic field (T)

x=0 x=0.1 x=0.2 x=0.3 x=0.4 x=0.5 x=0.6 x=0.7 x=0.8 x=0.9 x=1

Ca1-xSrxRuO3T = 30 K

-10

-5

0

5

10

x10-3

-0.4 0 0.4

XAS

1.20.80.4

0

-80

-60

-40

-20

0

20

40

x10-3

510500490480470460450Photon Energy (eV)

XA

SM

CD

(ar

b. u

nit

s)

Ca1-xSrxRuO3H = 2 TT = 30 K

Ru M2,3

SrRuO3

Ru M3Ru M2

x = 0 x = 0.3 x = 0.4 x = 0.5 x = 0.6 x = 0.7 x = 0.8 x = 0.9 x = 1

Ferro.

Para.


MCD signal increases with x and HLine shape does not change

J. Okamoto et al.

0 0.2 0.4 0.6 0.8 1.0

150

100

50

0

T (K)

x

ferromagnetic

paramagnetic

Phase diagram

SrRuO3

Mspin ~ 0.65 B

Morb ~ “0” B

Planned: Study of magnetic anisotropy using single crystals






概要概要

S. Kawasaki et al., J. Solid State Chem. 121,　 174(1996)

Helical antiferromagnetic-to-ferromagnetic Helical antiferromagnetic-to-ferromagnetic transition in SrFetransition in SrFe1-x1-xCoCoxxOO33

5 K, 1 T(●, ○, ×), 5 T(□)H=1 T

helical　　 ferromagnetic helical　　 ferromagnetic

3.0

2.5

2.0

1.5

1.0

0.5

0

1.0

0.5

0

820810800790780770

2.5

2.0

1.5

1.0

0.5

0.0

-0.5

XA

S (

arb

. un

its)

MC

D:

∫

d

SrFe1-xCoxO3 Co 2p XAST = 30 KH = 2 T

Co 2p3/2 Co 2p3/2

Photon Energy (eV)

x = 0.1

x = 0.1

x = 0.15

x = 0.15

x = 0.2

x = 0.2

x = 0.5

x = 0.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

2.0

1.5

1.0

0.5

0.0

750740730720710700690

6

5

4

3

2

1

0

-1

Photon Energy (eV)

XA

S (

arb

. un

its)

MC

D:

=

-

∫d

SrFe1-xCoxO3 Fe 2p XAST = 30 KH = 2T

Fe 2p3/2 Fe 2p1/2

x = 0

x = 0× 10

x = 0.1

x = 0.15

x = 0.2

x = 0.5

x = 0.5

x = 0.2

x = 0.15

x = 0.1

Fe 2Fe 2pp, Co 2, Co 2pp core-level MCD in SrFe core-level MCD in SrFe1-x1-xCoCoxxOO33

Magnetic moments at Fe and Co sites Magnetic moments at Fe and Co sites in SrFein SrFe1-x1-xCoCoxxOO33

helical　　　　　 ferromagnetic

Magnetic moment at Fe site

J. Okamoto et al., submitted to PRB

H = 2 T

helical　　　　　 ferromagnetic

Magnetic moment at Co site






概要概要

安達健五「化合物磁性　遍歴電子系」裳華房 (1996)T. Goto et al., PRB ‘97

Itinerant-electron metamagnetism in Co(SItinerant-electron metamagnetism in Co(S1-x1-xSeSex x ))22

M-H curves

K. Mamiya et al.

Co 2Co 2pp core-level MCD in Co(S core-level MCD in Co(S0.950.95SeSe0.050.05))22

XAS MCD

Spin and orbital moments in Co(SSpin and orbital moments in Co(S0.950.95SeSe0.050.05))22

K. Mamiya et al.

T. Goto et al., PRB ‘97

Spin and orbital moments in Co(SSpin and orbital moments in Co(S0.950.95SeSe0.050.05))22

K. Mamiya et al.

No change in spin/orbital moment ratio across Bc ?






概要概要

Ferromagentic superconductor UGeFerromagentic superconductor UGe22

S. S. Saxena et al., Nature ‘00A. Huxley et al., PRB ‘01N. Tateiwa et al., JPSJ ‘01

ferromagnetic

supercond.

TCurie = 52 K TSC = 0.8 [email protected] GPaT* ~ 30 K: anomaly ?

T*

T*

TCurie

new order parameter ?

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

42 K

36 K

33 K

30 K

25 K

U N4,5 XAS

N5N4

-0.15

-0.10

-0.05

0.00

840820800780760740720700

Photon Energy (eV)

U N4,5 MCD

42 K 36 K 33 K 30 K 25 K

1.0

0.8

0.6

0.4

0.2

0.0840800760720

T = 25 K

T. Okane et al.

T* TCurie

magnetization

MCD intensity (arb. units)

Mag

netiz

atio

n (

B)

U U NN4,54,5 MCD of UGe MCD of UGe2 2 : Temperature dependence : Temperature dependence

1120108010401000photon energy (eV)

MCD

1.0

0.5

0.0

UGe2

U N3 XAS

0.04

0.02

0.00

-0.02

-0.04

U U NN33 (4 (4pp 6 6dd), Ge ), Ge LL2,32,3 (2 (2pp 4 4ss)) MCD of UGeMCD of UGe22

T. Okane et al.

No polarization of U 6d electrons

Finite Ge L2,3 MCD Finite polarization of Ge 4s electrons

結論と展望結論と展望

• 低温（～１０ K ）、強磁場（～１０ T ）における MCD により、以下の研究が可能になる

– 複雑な磁気構造・磁気相転移について、磁化を元素に分離して調べる

– メタ磁性　‐　転移に伴う電子状態変化の探索

– 磁気異方性　‐　磁場方向に依存した軌道磁気モーメント

– 磁気的に不均一な系　‐　希薄磁性半導体？

– 常磁性状態、反強磁性状態　‐　誘起モーメントを見る

– ウラン化合物　

Documents

物性研短期研 究会「遍歴系の特異な磁性と磁性材料への応用」 2004 年 5 月 13 － 15 日

物性研短期研究会「遍歴系の特異な磁性と磁性材料への応用」 2004 年 5 月 13 － 15 日