HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
BRAZILIAN CENTER FOR RESEARCH IN PHYSICS- CBPF / MCT www.cbpf.br
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
CBPF - National Institute/MCT
www.cbpf.br
Rio de Janeiro
Jacques Danon
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Elisa Baggio Saitovitch
Julian Munevar, CBPFMariella Alzamora, CBPF
Dalber Sanchez-Candela, UFF
Magnetic and Structural Transitions in the New Fe-pnictide Superconductors
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
G. F. Cheng and N. L. WangInstitute of Physics, Chinese Academy of Sciences, Beijing, Peoples Republic of China
S. L. Budko and P. C. CanfieldAmes Laboratory, U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, USA
Tomo UemuraColumbia University , NY, USA
Graeme LukeMcMaster University, ON, CanadaCIAM Collaboration Program (NSF/CNPq)
Hai Hu Wen IOP, National Superconductivity Laboratory, China
Collaborators Samples grown - Physical characterization
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Hideo Hosono started with Iron-Based Layered SC: LaOFeP (Tc=6K) to SmFeAsO1-x (Tc= 55 K)
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Iron-based layered compound LnOFeAs “1111 phase”
The discovery of superconductivity in fluorine doped LaFeAsO superconductor with TC = 26 K* has generated enormous interests in the community of superconductivity
**Hiroki Takahashi, Nature 453, 376 (2008)
F-substitutionLaFeAsO1-xFx
*Y. Kamihara, et al, J. Am. Chem. Soc. 130, 3296 (2008).
Ln substitution (Gd3+Th4+)
Cao Wang et al EPL 83 67006 (2008)
Tc up to 56K for (Gd,Th)FeAsO
O-deficiencyLnFeAsO1-y
Z.A. Ren et al. Europhys. Lett. 83 17002 (2008)
Tc=55 K in SmFeAsO1−δ
LaOFeAs -> (Tc = 26 K) SC under • doping with F–
• oxygen deficiency
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
*D. Johrendt and R. Pottgen, Angew. Chem. Int. Ed. 47, 4782 (2008).
The crystal is composed of a stack of alternating REO or A and FeAs layers.
122 AFe2As2 A=Ba, Ca Sr, Eu
Iron-arsenide- 1111 and 122 Phases
1111 ROFeAs R=La, …….., Gd
Fe has tetrahedral coordination and is formally divalent
Fe
As
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
In 2008
More than 700 papers
Increase of TC of RE(O,F)FeAs superconductor after announcement by Hosono on Feb., 2008, made by Chinese physicists including PI Wang and LE Wen
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
LnFePO Tc~5-6 K ( Tc~8.8K at Pressure ~0.8 GPa)
LnFeAsO1-xFx LaFeAsO1-xFx x=0.11, Tc~26K (Tc~43K at P~4GPa) CeFeAsO1-xFx x=0.16, Tc~41K
SmFeAsO1-xFx x=0.10, Tc~43K NdFeAsO1-xFx x=0.11, Tc~52K PrFeAsO1-xFx x=0.11, Tc~52K TbFeAsO1-xFx Tc~46K (x=0.1, 0.2) DyFeAsO1-xFx Tc~45K (x=0.1, 0.2)
LnFeAsO1-x LaFeAsO1-x 31.2 CeFeAsO1-x 46.5
PrFeAsO1-x 51.3 NdFeAsO1-x 53.5 SmFeAsO1-x 55.0 GdFeAsO1-x 53e TbFeAsO1-x 52 DyFeAsO1-x 52
(Ln,RE)FeAs (La1-xSrx)FeAsO Tc~ 25K(x=0.13), hole-doping Gd1-xThx)FeAsO Tc~56K (x=0.2), electron-doping
Ca(Sr)FeAsF Ca(Fe1-xCox)AsF Tc~22K (x=0.10) [Ni2+(3d7) Fe2+(3d6)] Ca(Fe1-xNix)AsF Tc~12K (x=0.05) [Ni2+(3d8) Fe2+(3d6)] (Sr1-xLax)FeAsF Tc~32K (x=0.4)
CaFe2As2 Tc~27K (Pressure~3.0 GPa) (Ba1-xKx)Fe2As2 Tc~38K (x=0.4) (Sr1-xNax)Fe2As2 Tc~37K (x=0.4) Ba(Fe1-xCox)2As2 Tc~22K (x=0.1)
Li1-xFeAs Tc~18K
FeSe1-x Tc~8K (x=0.88), Tc~27 K (P~ 1.48 GPa) FeSe1-xTex Tc~15K FeTe1-xSx Tc~10K (x=0.2), non-toxic
Catalogue of Fe-based Superconductors
Fe-1111
Fe-122
Fe -111
Fe-11
Fe-42622Sc 42622 V 42622
RFeAsO1-xFx , AFe2As2, Sr4A2O6Fe2As2 Fe-1111 Fe- 122 Fe - 42622
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
LnFePO Tc~5-6 K ( Tc~8.8K at Pressure ~0.8 GPa)
LnFeAsO1-xFx LaFeAsO1-xFx x=0.11, Tc~26K (Tc~43K at P~4GPa) CeFeAsO1-xFx x=0.16, Tc~41K
SmFeAsO1-xFx x=0.10, Tc~43K NdFeAsO1-xFx x=0.11, Tc~52K PrFeAsO1-xFx x=0.11, Tc~52K TbFeAsO1-xFx Tc~46K (x=0.1, 0.2) DyFeAsO1-xFx Tc~45K (x=0.1, 0.2)
LnFeAsO1-x LaFeAsO1-x 31.2 CeFeAsO1-x 46.5
PrFeAsO1-x 51.3 NdFeAsO1-x 53.5 SmFeAsO1-x 55.0 GdFeAsO1-x 53e TbFeAsO1-x 52 DyFeAsO1-x 52
(Ln,RE)FeAs (La1-xSrx)FeAsO Tc~ 25K(x=0.13), hole-doping Gd1-xThx)FeAsO Tc~56K (x=0.2), electron-doping
Ca(Sr)FeAsF Ca(Fe1-xCox)AsF Tc~22K (x=0.10) [Ni2+(3d7) Fe2+(3d6)] Ca(Fe1-xNix)AsF Tc~12K (x=0.05) [Ni2+(3d8) Fe2+(3d6)] (Sr1-xLax)FeAsF Tc~32K (x=0.4)
CaFe2As2 Tc~27K (Pressure~3.0 GPa) (Ba1-xKx)Fe2As2 Tc~38K (x=0.4) (Sr1-xNax)Fe2As2 Tc~37K (x=0.4) Ba(Fe1-xCox)2As2 Tc~22K (x=0.1)
Li1-xFeAs Tc~18K
FeSe1-x Tc~8K (x=0.88), Tc~27 K (P~ 1.48 GPa) FeSe1-xTex Tc~15K FeTe1-xSx Tc~10K (x=0.2), non-toxic
Catalogue of Fe-based SuperconductorsFe-1111
Fe-122
Fe -111
Fe-11
Fe-42622Sc 42622 V 42622
RFeAsO1-xFx , AFe2As2, Sr4A2O6Fe2As2 Fe-1111 Fe- 122 Fe - 42622
RFeAsO1-xFx , AFe2As2, Sr4A2O6Fe2As2 Fe-1111 Fe- 122 Fe - 42622
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Ceramic polycrystalline specimens of RFeAsO1-xFx (R=Nd, Ce) were synthesized by G F Cheng and N. L. Wang at Institute of Physics, Chinese Academy of Sciences, Beijing
EXPERIMENTAL INFORMATION
Mössbauer experiments were performed at CBPF, Rio de Janeiro with an Oxford cryostat in sinusoidal mode with transmission geometry, with 57Co:Rh source and sample at the same T
Single crystals of AFe2As2 (A=Ca,Ba, K) were synthesized at Ames National Lab., Ames, USA and N. L. Wang Sr4A2O6Fe2As2 (A=Sc,V) Oxypnictides polycrystalline specimens were provided by Hai-Hu Wen, from National Lab. Superconductivity, BeijingµSR performed by Uemura group in TRIUMF on some samples with participation of Julian Munevar and Dalber Sanchez
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Mössbauer Spectroscopy in RNi2B2C and RNiBC with 57Fe at Ni site• information about local symmetry and magnetic order• Bhf at the 57Fe nucleus, due to non collinear AF spin structure
of the RE moments, acts as a pair-breaking field at the Ni site
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
TbNi2B2C4%
Relat
ive Tr
ansm
ission
Velocity (mm/s)
3K
4.2K
7.4K
9K
12.5K
15K
0 2 4 6 8 10 12 14 16 18
0.0
0.2
0.4
0.6
0.8
1.0
1.2
TbNi2B2C
(de
g.)
B hf (T)
Temperature (K)
60
75
90
105
120
TN
TW
F
TbNi2B2C
Previous Studies
R
Ni (Fe)BC
ab
c
RNi2B2C
Magnetism is due exclusively to R magnetic moments: AF, FM, WFM, and SDW determined by coupling of R layers
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Superconductivity and Magnetism in HoNi2B2C
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
4%HoNi2B2C
Relat
ive tra
nsmi
ssion
Velocity (mm/s)
4.2K
3K
4.7K
4.9K
5.1K
5.5K
5.3K
Reentrant behavior and incommensurate modulated magnetic structure for 4.6T6 K
Evidence of pair-breaking field at the Ni (57Fe)
D. R. Sánchez, H. Micklitz, M. B. Fontes, S. L. Bud’ko and E. Baggio Saitovitch, Phys. Rev. Lett. 76, 507 (1996)
Ho
a b
c
HoNi2B2C
2
3
4
Ho
Ni (Fe)
Ho
T<8K4.2K<T<6KT<4.2K
0 2 4 6 8 10 12-5-4-3-2-1012
HoNi2B2C
Temperature (K)
'(u.
a.)
0.0
0.2
0.4
HoNi2B2C
B hf (T)
0 2 4 6 8 10 12
-5-4-3-2-1012
HoNi2B2C
Temperature (K) '(
u. a.) 0.0
0.2
0.4
HoNi2B2C
B hf (T)
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
R-layer
Ni (Fe) Ni-layer
Ni (Fe)
B =0
B 0
hf
hf
collinear AFM
Noncollinear AFM
R-layer ithfBhfB isi
No Bhf field was observed at any temperature below TN for the AFM superconductors ErNi2B2C and DyNi2B2C
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
LaOFeAs - 111 BaFe2As2- 122
Structures of Fe-As: RFeAO , AFe2As2 and Sr4A2O6Fe2As2
Structure: Tetragonal P4/nmm Tetragonal I4/mmm Tetragonal P4/nmmStructural transition: ~ 155K ~ 140K NONE
Magnetic ordering: ~ 140K ~ 140K 36 KSuperconductor: with F dop & O deficiency withr K, Ca, Co doping A=V
Sr2(V/Cr)O3FeAs
Local structure at Fe site is similar different Fe moments and 3d Fe contribution in the density of states at EF level
Sr2AO3
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
LaOFeAs
LaOFeAs has long range SDW-type AF order at ~134 K with Fe=0.36B
LaOFeAs has structural distortion below ~150 K
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
NdOFeAs and CeOFeAs
Fratini M, Supercond. Sci. Technol. 21, 2008. Ying Chen, Phy. Rev. B 78, 2008. Y. Qiu, Phys. Rev. Lett. 101, 2008.
NdOFeAs CeOFeAsTS (P/4nmm-Cmma) ~ 150K ~158K TN (Fe) ~ 141K ~ 140 KFe ~ 0.32 B ~ 0.6 B TN(R) ~ 2K ~ 4K
NdFeAsO1-xFx and CeFeAsO1-xFx Electron-doping by F – substituting for O2- increases Tc to about 50 K.
G. F. Chen, Phys. Rev. Lett. 100, 247002 (2008) and Chin. Phys. Lett. 25, 2235 (2008). Jun Zhao, Nature Materials 7, 953 (2008)
NdNd Ce
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
NdFeAsO0.88F0.12 and NdFeAsO
Room temperature MS
RT NdFeAsO: small impurities, FeAs (~ 8%) and FeAs2 (~5%). The main component (doublet) is attributed to Fe in NdFeAsO phase and their hyperfine parameters are almost the same as for NdFeAsO0.88F0.12
RT NdFeAsO0.88F0.12 spectrum: unique phase, similar to that found for LaOFeAs*
EQ=0.02(2) mm/s IS=0.437(1) mm/s,
*H.-H. Klauss et al., Phys. Rev. Lett 101, 077005 (2008). -3 -2 -1 0 1 2 3
NdOFeAs FeAs FeAs
2
Rel
ativ
e Tr
ansm
issi
on
Velocity (mm/s)
5%
NdO0.88F0.12FeAs5%
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
The magnetic transition at ~ 140K is due to the magnetic ordering of Fe moments.
Below ~2K an additional increase of Bhf, : transferred Bhf at Fe due to collinear AF order of Nd moments.
(EQ → measure of the As Tetrahedra)
SR results* support our model used to analyze our Mössbauer spectra.
*A. Aczel, et al., Phys. Rev. B 78, 214503 (2008)
0
1
2
3
4
5
6
TN(Fe)
Bhf
(T)
TN(Nd)(a)
0
20
40
60
80
100
(b)
Para
mag
netic
frac
tion
(%)
0 20 40 60 80 100 120 140 160-0.04
0.00
0.04
0.08
0.12
0.16
(c)
EQ(m
m/s
)
Temperature (K)
Results for NdFeAsO
-3 -2 -1 0 1 2 3
1.5K
Velocity (mm/s)
6%
4.3K
40K
90K
126K
Rel
ativ
e Tr
ansi
mis
sion
135K
150KNdOFeAs
0 20 40 60 80 100 120 140 160
0
1
2
3
4
5
6
Bhf (I) 82%
B hf (T
)
Temperature (K)
NdFeAsO
Bhf (II) 18%
CM1 : (I) = 90 ± 5o, commensurate AF structure with the Fe spins lying in the (a,b)CM2: (II) ≈ 55o, all angles in the range 0 90o occur with equal probability
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
No hyperfine magnetic field was observed at 57Fe nucleus [Bhf(1.5K) 0.1T] of Fe in superconducting NdFeAsO0.88F0.12 at any temperature (down to 1.5K)
Absence of magnetism in this compound
Results for SC NdFeAsO0.88F0.12
Low temperature MS
-3 -2 -1 0 1 2 3
1.56K
Velocity (mm/s)
6%
4.35K
35K
50K
NdO0.88F0.12FeAs
295K
Rel
ativ
e Tr
ansm
issi
on
TC ~ 45K
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
All spectra were fitted with single lines
The Bhf field at Fe nucleus decreases with F content and disappears for x=0.16. Magnetism suppressed by F doping.
-3 -2 -1 0 1 2 3
x=0.16
Velocity (mm/s)
5%
x=0.10
x=0.08 Rel
ativ
e in
tens
ity
x=0.06
T=295K
x=0.04
x=0.0
-3 -2 -1 0 1 2 3
x=0.16
Velocity (mm/s)
5%
x=0.10
x=0.08
Rel
ativ
e in
tens
ity
x=0.06
T=4.2K
x=0.04
x=0.0
Results for in CeFeAsO1-
xFx Room temperature MS 4.2K MS
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Neutron studies [13] Jun Zhao, et al., Nature Materials 7, 953 - 959 (2008).
0.00 0.04 0.08 0.12 0.16 0.200
1
2
3
4
5
6
0
20
40
60
80
100
Bhf
(T)
x (F)
CeO1-xFxFeAs 4.2K
Magnetic order T c (K
)
Superconductivity
Mössbauer results shown a region of coexistence of superconductivity and magnetism (phase separation).
For CeOFeAs Fe ≈ 0.39 B
CeFeAsO1-xFx phase diagram
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
MS with different T
Fe spins ordering at ~145K lying in the (a,b) plane
Results for CeFeAsO
0 20 40 60 80 100 120 140 160 180
0
2
4
6
8
TN(Ce)
Bhf
(T)
Temperature (K)
CeFeAsO
TN(Fe)
-4 -3 -2 -1 0 1 2 3 4
T = 4.3KBext = 7 T
Rel
ativ
e in
tens
ity
Velocity (mm/s)
T = 4.3KBhf ~ 5.5TBext= 0 T
CeFeAsO under applied external field
Ce moments order at ~5K
Beff =Bext + Bhf A fraction of Fe spins tend to align parallel (Beff ~ 12 T) and the remaining ones antiparallel (Beff ~ 3 T) to the external field
MS support the AFM ordering of Fe spins
Beff ~ 12 T and 3T
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
No Bhf was observed at 57Fe nucleus in NdFeAsO0.88F0.12 and CeFeAsO0.84F0.16 down 2K
Doping with F suppresses both the magnetic order and structural distortion in favor of superconductivity
The Bhf in NdFeAsO and CeFeAsO can be associated to SDW AFM order of Fe spins below ~140 and ~145K, as seen by neutrons
The AFM ordering of Nd and Ce spins seen by neutrons at ~2K and ~ 5K generate additional Bhf
Fe magnetic moment estimated to be ~0.35 B in NdFeAsO and ~0.39 B in CeFeAsO. Similar to neutron data
Coexistence (phase separation) of SC and magnetism has been observed in CeFeAsO1-xFx for 0.05 x 0.11.
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
- Structural transition (Tetr to orthorhombic) at ~ 170K
- Order of the Fe moments, in a commensurate AF structure.
A.I. Goldman et al., Phys. Rev. B 78, 100506R (2008)
*Pressure Induced Superconductivity in CaFe2As2.
A. Kreyssig et al., Phys. Rev. B 78, 184517 (2008)Milton S. Torikachvili et al., PRL 101, 057006 (2008)
T. Goko, Uemura, Sanchez, Saitovitch et al. Phys. Rev. B78, 214503 (2009) SR
Ternary iron-arsenide CaFe2As2
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
EQ=0.207 mm/sIS=0.44 mm/s=0.26 mm/sφ ≈10o
EQ=0.339 mm/sBhf= 9.95T Angle between Vzz and Bhf: ≈ 85o5o
BhfVZZ
a
b
c
CaFe2As2 single crystal
Fe≈ 0.66 B and lie in a-b plane(agrees with neutron results)
Only one site at low T
Mariella
VZZ
a
b
c
φ
Sample
VZZ
a
b
c
φ
Sample
55o
c
c
c //
-3 -2 -1 0 1 2 3
4.2 K
Rel
ativ
e tr
ansm
issi
on
Velocity (mm/s)
295K
CaFe2As2 mosaic crystal sites
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Jump in Bhf(T) at ~180K, typical for a first-order transition
182K
180K
170K
Rela
tive
trans
mis
sion
150K
65K
-4 -2 0 2 4
4.3K
Velocity (mm/s)
6%
CaFe2As2 (T)
0 50 100 150 200
0
2
4
6
8
10
0.0 0.2 0.4 0.6 0.8 1.0 1.20.0
0.2
0.4
0.6
0.8
1.0
B hf(T
)/Bhf(4
.2K)
T/T0
=1.3
B hf(T
)
Temperature (K)
TN
0 50 100 150 200 250 300
0.20
0.24
0.28
0.32
0.36
0.40
EQ (m
m/s
)
Temperature (K)
0 50 100 150 20070
80
90
100
(de
g.)
Temperature (K)
Structural transition
commensurate AFM ordering with Fe spins lying in the (a,b) plane
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Hole doped AFe2As2 (with K or Na) shows a phase separation at low temperature with a fraction of Fe ions in a paramagnetic state while remaining ones have a magnetic moment reduced related to undoped, order magnetically TO > Tc.
This two phases are indistinguishable at room temperature
Same behavior is observed for Co doped BaFe2As2 with the difference that in this case the doping is being performed at the Fe site
In all the cases the doping distribution seems not to be homogeneous
Vzz in CaFe2As2 was found to be parallel to c.
Only one Fe site showing a first order transition at ~ 140K with the Fe spin lying in the (a,b) plane
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Sr4A2O6Fe2As2 Iron Pnictides
(so-called 42622), with a perovskite layer between FeAs layers,
M. Tegel et. Al, Zeitschrift fur anogarnische und allgemeineChemie, V 635, 2242 (2009)X. Zhu et. Al, Physical Review B 79, 220512(R), (2009)Y. L. Xie et al, Europhysics Letters 86, 57007 (2009)
- No SDW ordering- No structural transition- Large Fe-Fe interlayer distances (~15 Å)
- TC= 37 K for SrVOFeAs- 0. 1 T transferred field to Fe in SrVOFeAs
- No SDW in SrScOFeAs
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
δ=0.297(2) mm/s ΔEQ=-0.256(2) mm/s
Sr4V2O6Fe2As2
μSR show strong static magnetism below 100 K, increasing volume fraction for low temperature
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Possible coexistence of magnetic ordering in V atoms and superconductivity in FeAs layers in SrVOFeAs
Magnetic ordering found for SrScOFeAs does not correspond to SDW or incommensurate-commensurate magnetic ordering
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Perspectives for Mössbauer in the studies of Unconventional SC
Follow details at local level of magnetic transitions
Determine the structural phase transition and any special related feature
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
Thank youFAPERJ, Pensa Rio, Infra estrutura , Cientista do EstadoPRONEX, CNPq (CIAM, DFG)CAPES (PROBRAL)
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
TEAM
peElisa Baggio Saitovitch Pesquisador Titular III (CNPq – 1A)Magda Bittencourd Fontes Pesquisador Associado IIIMarcos de Castro carvalho Mestre Tecnologista
PESQUISADORES VISITANTES ESTRANGEIROSManfred Forker CNPqHans Micklitz CNPq
POS DOUTORANDOSEduardo Hering Novaes FAPERJMariella Alzamora Camarena CLAF-CNPqUrbano Miguel Tafur Tanta CLAF-CNPq /CNPqScheilla Maria Ramos da Silva PNPD CNPqWillian Alayo Rodriguez FAPERJYutao Xing FAPERJ/PCI-CNPq
ALUNOS DE DOUTORADOIsabel Dinola FAPEAMJulian Munevar Cagigas CNPqJustiniano Quispe Marcatoma BIDKumaresavanji Malaivelusamy CNPq-TWASWilliam Trujillo Herrera Mestre CLAF-CNPq
ALUNOS DE MESTRADOUry Denver Chacón Hernandez CNPq
HFI-NQI 2010, 12-17 September 2010 CERN, Geneva
BRAZILIAN CENTER FOR RESEARCH IN PHYSICS- CBPF / MCT www.cbpf.br
We are looking for Pos docs to work in:Mossbauer, PAC, magnetization and transport under pressureMagnetic Multilayer, SC, Oxides, Heavy Fermions!