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Nanomagnetism,oxides and resonance laboratory
Service de Physique de l’Etat
Condensé
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•
9 permanent researchers
•
4 technicians, 2 electronic engineer
•
5 PhD students , 5 post-docs
+Associated teams for Neutrons and NMR
The team
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• Magnetism at small scales
– Thin films and nanostructures – Transport
– Dynamics
• Oxides (superconductors and multiferroics)
• Mössbauer, NMR and NQR
• Spin electronics based magnetic sensors
Research axis
0 100 200 300 400
0 100 200 300
ρ (μΩ.cm)
T (K)
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Synthesis and characterization
of cuprates, iron-pnictides and multiferroic oxides
A. Forget, D. ColsonSingle crystal growth by flux
Synthesis of ceramics by solid state reaction
BiFeO3 :1 ferroelectric domain crystal
A multiferroic with Ps= 100 μC/cm2 at 300K !
0 100 200 300 400
0 100 200 300
ρ (μΩ.cm)
T (K)
First single crystals of mercury cuprates (1994)
Tc=95K for HgBa2 CuO4+d
PS[111]
K+: 4s1
Hole doped (Tcmax ~ 38K)
Ru2+:4d75s1 Isolelectronic of Fe
Co2+: 3d7 Ni2+: 3d8 electron‐doped
P3‐: 3s23p3
Isolelectronic of As
(Tcmax ~ 25K)
Iron pnictide superconductor Ba(Fe1-x Mx )2 As2 single crystals
Characterization:
X-ray mesasurements, thermogravimetric analysis Squid magnetometry
Lebeugle D., Colson D., Forget A., Viret M, Appl.
Physics Lett. 91 22907 (2007)
Raman: Gallais, Y.; Le Tacon, M.; Sacuto, A.; Colson, D, Europhysics Letters (2006), 73(4), 594-600.
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Transport Properties in Superconducting High-T
cCuprates and Iron-based Pnictides
Measurements of resistivity, Hall effect and magnetoresistance
Study of the transport properties in Co and Ru substituted Ba2 Fe2 As2
-1.5 -1 -0.5 0 0.5 1
RH (10-9 m3 /C)
0 0.05 0.19 0.44
0.26
0.35 Ba(Fe
1-xRu
x)
2As
2
(a)
-3 -2.5 -2 -1.5 -1 -0.5
0 50 100 150 200 250 300
RH (10-9 m3/C)
T (K) 0.014 0 0.06
0.07 0.12 0.2
Ba(Fe
1-xCo
x)
2As
2
(b)
Evidence for different contributions of electrons and holes to the transport properties
Determination of superconducting fluctuations in YBa2 Cu3 O6+x by high-field magnetoresistance measurements
In the optimally doped sample, the pseudogap temperature is below the onset of superconducting fluctuations (SCF)
The pseudogap phase cannot be considered as a percursor state for superconductivity
Hole doping nh T
?
Pseudogap line
SCF SC F. Rullier-Albenque, D. Colson, A. Forget, H. Alloul, PRL 103,057001 (2009)
F. Rullier-Albenque, D. Colson, A. Forget et al., PRB 81, 224503 (2010).
F. Rullier-Albenque, H. Alloul, G. Rikken, PRB 84, 014522 (2011).
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Photovoltaic effect of BiFeO3 single crystals
0 5 0 10 0 150 2 00 25 0
-0,3 -0,2 -0,1 0,0 0,1 0,2
BFO BFOBFO
BFO BFO
E1
I (nA)
T im e (m in )
E1
E2 E2
E1
E2 E1
E2
E1
B iFeO3
s in g le cry s tal G o l d e le c tr o de
V A
Sp a c i ng o f 2 5 µ m
G l a ss pl a te
Multiferroics
Photostriction inBiFeO3.
BiFeO3 is ferroelectric and antiferromagnetic Photons related effects
B. Kundys, M. Viret, D. Colson and D. O. Kundys, Nature Materials 9, 803 (2010).
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Magnetic atomic contacts
0 3 6 9 12 15
-1 -0.8 -0.6 -0.4 -0.2 0
d (nm) σ (2e2 /h)
Ferromagnetic resonance
In atomic contacts and nanobridges
A. Ben Hamida, O Rousseau, S Petit-Watelot and M Viret, Europhys. Lett. 94, 27002 (2011).
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Dynamics of a magnetic Vortex probed by MRFM
Low temperature MRFM:
- magnetic nanoparticles - new materials
Magnetization dynamics in spin transfer nano-oscillators
Experimental development
Vortex core reversal induced by RF pulses
Identification of the spin-wave modes
Magnetization dynamics in nannostructures
B. Pigeau, et al, Nature Physics, 7, 26-31 (2011).
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-0.008 -0.006 -0.004 -0.002 0 0.002 0.004 0.006 0.008
0 50 100 150 200 250 300 350 400
2D Compas for watch Magnetic imaging,NDE Current sensors for fuel cells
Read heads, current sensors for electricity meters and failure surveillance, Rotational switches
Spin electronics based Magnetic sensors
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Biochips
Sensors for medical applications
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Femto Tesla sensors for low field MRI and biomagnetism
Sensors for medical applications
Common MEG lab at Neurospin
Magneto Cardiography Very low field MRI
