the effect of superconducting current on the magnetic phase transition in lsco films

Physics Department, Technion, Israel

Meni Shay, menishay@braude.ac.ilOrt Braude College, Israel andPhysics Department, Technion, Israel

Phys. Rev. B 80, 144511 (2009)

LEM group, PSI,Switzerland

Amit Keren Gad KorenAmit KanigelDaniel Podolsky

Gerard NieuwenhuysElvezio MorenzoniAndreas SuterThomas Prokscha

Theoretical and Experimental Magnetism Meeting8-9 September, 2010

SG

Does the super-current impact the magnetic state?

Research Question

A Picture Without a Model

Katano, S., Sato, M., Yamada, K., Suzuki, T., Fukase, T. “Enhancement of static antiferromagnetic correlations by magnetic field in a superconductor La2-xSrxCuO4 with x=0.12” Phys. Rev. B 62, R14677-R14680 (2000).

Lake B. et al. “Antiferromagnetic order induced by an applied magnetic field in a high-temperature superconductor” Nature 415, 299-302 (2000).

D. Haug et al. “Magnetic-field-enhanced incommensurate magnetism in the underdoped high-temperature superconductor YBa2Cu3O6.45”, Phys. Rev. Lett. 103, 017001 (2009).

Works along this line

How to do it?

• Take a s.c. wire • Hold it at a constant

known temperature T<Tm

• Flow high current through it ~ Jc

• Measure its internal magnetic order as a function of current

Jc~105 A/cm2 A thin wire is needed

Using muon spin rotation of Low energy muons (LEM)

Sample

Samples are prepared in the Technion in Gad Koren’s Lab

300μ

2”

A long (8m) and thin (0.5x100μm2) meander La1.94Sr0.06CuO4 wire

5 10 15 20 250.0

0.1

0.2

0.3

246

0

3

6

9

Rsc

(s

ec-1

)

Temperature (K)

b

Res

isti

vity

(m

cm)

Temperature Calibration

4 6 8 10 120

5

10

15

20

T (K)

Ic1

I c1,I

c2 (

mA

) Ic2

0 5 10 15

0

10

20

30

I (mA)

45

67

8

9

V (

mV

)

T=12 K

Temperature accuracy ~ 0.01 K

Results – from Bulk samples (GPS)

BM 0.33

Results

0 2 4 6 8

0.1

0.2

Asy

mm

etry

Time (sec)

T(K), I(mA) =

7.35, 0.5 5.0, 0.5 5.0, 4.0

2.9, 0.5 3.85, 5.0

1 2 3 40.05

0.10

0.15

0.20

Asy

mm

etry

Time (sec)

T=5.003(5)K I=0.5mA Run 1775 T=4.993(6)K I=1.0mA Run 1780 T=5.002(5)K I=1.5mA Run 1778 T=5.006(5)K I=2.5mA Run 1777 T=4.998(16)K I=3mA Run 1782 T=4.997(11)K I=3.3mA Run 1783 T=5.001(8)K I=3.7mA Run 1776

Results

3 4 5 6 7 80.0

0.5

1.0

M

Temperature (K)

Low Current T

m=5.37 K 0.05

High Current T

m=5.77 K 0.05

Tm=0.4K0.1

Interpretation &

Analysis

Ginzburg-Landau Model for two interacting order parameters with

chemical potential

Special Case: SO(5) Theory Demler et. al. Rev. Mod. Phys. 76 909 (2004).

2 4( ) sF a T U

2 4( ) mb T U

2 2

smU 2

2 4( ) sG a T U

The GL params are known

20

20

2 * 2

2 * 2

2 * 2 20 0

2 20

2 *

2

/ 2

( ) 2

2

4

/

s

m m

m

U a

U bT

a T m

bT m

m e

M v

m A J

2

B

2nm

4nm

500nm

1000K

15Å

M 0.33

J

A

Theory Experiment

m

600K

U 40KsU

Integrated over a unit cell

changes with I through the interaction term

2 20

22

2T T ( ) T (0) smm m m

c

U II

b I

The magnetic transition temperature, Tm, changes when

current is applied

Prediction

Start from GL free energy

216KsmU

2 42 22

2 4

2 2

1 / c s

m m

sm

F a T I I U

b T T U

U

Integrated over a unit cell

Conclusions

The temperature of the magnetic phase transition

is increased by the flow of astrong superconducting current

1sm

s m

U

U U