Meni Shay, menishay@braude. ac. il Ort Braude College, Israel and Physics Department, Technion, Israel LEM group, PSI, Switzerland Physics Department, Technion, Israel Amit Keren Gad Koren Amit Kanigel Daniel Podolsky Gerard Nieuwenhuys Elvezio Morenzoni Andreas Suter Thomas Prokscha Theoretical and Experimental Magnetism Meeting 8 -9 September, 2010 Phys. Rev. B 80, 144511 (2009)
Research Question Does the super-current impact the magnetic state? SG
A Picture Without a Model
Works along this line Katano, S. , Sato, M. , Yamada, K. , Suzuki, T. , Fukase, T. “Enhancement of static antiferromagnetic correlations by magnetic field in a superconductor La 2 -x. Srx. Cu. O 4 with x=0. 12” Phys. Rev. B 62, R 14677 -R 14680 (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 YBa 2 Cu 3 O 6. 45”, Phys. Rev. Lett. 103, 017001 (2009).
How to do it? • Take a s. c. wire • Hold it at a constant known temperature T<Tm • Flow high current through it ~ Jc • Using muon spin Measure its internal magnetic order as a rotation of Low energy function of current muons (LEM) Jc~105 A/cm 2 A thin wire is needed
Sample A long (8 m) and thin (0. 5 x 100μm 2) meander La 1. 94 Sr 0. 06 Cu. O 4 wire 2” 300μ Samples are prepared in the Technion in Gad Koren’s Lab
Temperature Calibration Temperature accuracy ~ 0. 01 K
Results – from Bulk samples (GPS)
Results
Results
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).
The GL params are known Theory Experiment Integrated over a unit cell
changes with I through the interaction term Start from GL free energy Prediction The magnetic transition temperature, Tm, changes when current is applied Integrated over a unit cell
Conclusions The temperature of the magnetic phase transition is increased by the flow of a strong superconducting current
Скачать презентацию Meni Shay menishay braude ac il Ort Braude College
f38e723bd0743831ce5e50c7ba04348c.ppt