Coexistence of long range magnetism
and superconductivity
Krzysztof Rogacki
Institute of Low Temperature and
Structure Research, PAS,
Wroclaw, Poland
&
International Laboratory of High
Magnetic Field and
Low Temperatures, PAS,
Wroclaw, Poland
SYMPOZJUM DOKTORANCKIE
Institute of Physics PAS Warsaw 7 April 2016
COEXISTENCE OF LONG-RANGE ORDERS IN SOLIDS
Overview
superconductivity and AFM in classic/low-Tc
superconductors (CSC/LTSC)
Summary
anomalous flux penetration into CSC with AFM
ordering
superconductivity and long range magnetism:
introduction, interplay, coexistence
superconductivity and AFM ordering in high-Tc
superconductors (HTSC)
superconductivity and FM ordering in Y9Co7
superconductivity and FM ordering in unconventional
(UCSC) superconductors
Overview
superconductivity and AFM in classic/low-Tc
superconductors (CSC/LTSC)
Summary
anomalous flux penetration into CSC with AFM
ordering
superconductivity and long range magnetism:
introduction, interplay, coexistence
superconductivity and AFM ordering in high-Tc
superconductors (HTSC)
superconductivity and FM ordering in Y9Co7
superconductivity and FM ordering in unconventional
(UCSC) superconductors
Summary
Type-II superconductivity:
R = 0 ; T Tc , j jc, H Hc2
B = 0, Meissner state; H Hc1
Microscopic mechanism
(BCS theory): Tc 30 K
Cooper pairs
condensation of pairs (phase coherent state)
odległość koherencji
spin
s = 0
s = 0
s = 1 ........
orb. mom.
l = 0
l = 2
l = 1 ........
sym.
s
d
p ........
superconductivity
classic
unconventional
Hc2
jc
Tc
Hc1
H
T
j
„inverted“ RKKY
exchange interaction
• magnetism is weak
• superconductor is
a HF type
basic properties of superconductors (coexistence of two competing phenomena)
nature of superconductivity in:
• UCSC (H. Suhl, PRL 87, 167007 (2001); A.A. Abrikosov,
J.Phys.: Condens. Matter 13, L943 (2001))
• HFSC (CePt3Si; E. Bauer et al., PRL 92, 027003 (2004))
Why the interaction between localized
magnetism and superconductivity is important ?
„inverted“ RKKY
exchange interaction
• magnetism is weak
• superconductor is
a HF type
basic properties of superconductors (coexistence of two competing phenomena)
nature of superconductivity in:
• UCSC (H. Suhl, PRL 87, 167007 (2001); A.A. Abrikosov,
J.Phys.: Condens. Matter 13, L943 (2001))
• HFSC (CePt3Si; E. Bauer et al., PRL 92, 027003 (2004))
Why the interaction between localized
magnetism and superconductivity is important ?
application of superconductors:
• improving critical currents (E.W. Hudson et al.,
Nature 411, 920 (2001))
• ”switching off/on” the superconducting state (?)
1957 – theory; V.L. Ginzburg,
Sov. Phys. JETP 4, 153 (1957)
1958 – La1-xREx; B.T. Matthias et al.,
Phys. Rev. Letters 1, 449 (1958)
…….
1976 – review; M.B. Maple,
Appl. Phys. 9, 179 (1976)
(influence of paramagnetic impurities on superconductivity; the summary)
Interplay between magnetism and
superconductivity (history)
______________
1975 – REMo6S8; Ø. Fischer et al.,
Solid State Commun. 17, 21 (1975)
1975 – REMo6S8; Ø. Fischer et al.,
Solid State Commun. 17, 21 (1975)
1976 – REMo6Se8; R.N. Shelton et al.,
Phys. Lett. 56 A, 213 (1976)
1977 – RERh4B4; W.A. Fertig et al., B.T. Matthias,
M.B. Maple,
Phys. Rev. Lett. 38, 987 (1977)
Localized AFM and superconductivity in LTSC
(UPt3, URu2Si2, UNi2Al3, UPd2Al3)
1994 – RENi2B2C; R.J. Cava et al., C. Mazumdar et al.,
R. Nagarajan et al.
Localized AFM and superconductivity in HTSC
1987 – REBa2Cu3O7; M.K. Wu, P.H. Hor, C.W. Chu
1997 – RuSr2RECu2O8; H.F. Braun et al. (1995),
I. Felner et al., J.L. Tallon et al.
Itinerant FM and LTSC
2000 – UGe2 ; S.S. Saxena et al., Nature 406, 587 (2000)
2001 – ZrZn2 ; C. Pfleiderer et al., Nature 412, 58 (2001)
2001 – URhGe ; D. Aoki, et al., Nature 413, 613 (2001)
(weak itinerant
FM and LTSC)
______________
1980 – Y9Co7; A. Kołodziejczyk et al.,
J. Phys. F 10, L33 (1980)
“super
coexistence” (Y9Co7, UGe2)
band electrons
contribute both
to magnetism and
to superconductivity
Definition of the coexistence of magnetism
and superconductivity
no coexistence (space separation)
a > , no coexistence (?)
a < , coexistence !
magnetic ions
a
a
Overview
superconductivity and AFM in classic/low-Tc
superconductors (CSC/LTSC)
Summary
anomalous flux penetration into CSC with AFM
ordering
superconductivity and long range magnetism:
introduction, interplay, coexistence
superconductivity and AFM ordering in high-Tc
superconductors (HTSC)
superconductivity and FM ordering in Y9Co7
superconductivity and FM ordering in unconventional
(UCSC) superconductors
Classic magnetic superconductors (4f - 4d)
REMo6S8 RERh4B4
What kind of the interaction is important for the interplay
between magnetism and superconductivity we observe ?
Interaction between localised spins and conduction
electrons in magnetic superconductors:
socalled sf interaction
g mB I +s S
sf coupling constant
electron localized spin
electromagnetic interactions
minimal interaction dipole interaction
- j(+,) a
total current
vector potential
magnetic induction
- g mB b S
Typical anomalous features observed
for classic AFM superconductors
localized long-range AFM order
and superconductivity interact
an increase of the pairbreaking
effects are expected due to
enhanced magnetic fluctuations
near TN
pronounced anomaly in
R(T) and (T) near TN 0.0 0.5 1.0 1.5 2.0 2.5
-1.0
-0.5
0.0
0
5
10
15
20
Gd1.07
Mo6.3
S8
H (kOe)
ac
(a.u
.)
Temperature (K)
0 0.1 0.3
H (kOe)
R (
m
)
0 0.1 0.3 0.6 1.0
Tc
TN
TN
Typical approach to study the interaction
between magnetism and superconductivity
T (K)
Hc2(T) and Hc1(T) can be
analyzed in the frame of:
sf exchange interaction
electromagnetic interaction
……..… ?
For high-Tc cuprates:
Hc2 ~ 150 T at TN ~ 1 K
Hc2 (
kO
e)
Hc1 (k
Oe
)
GdMo6Se8
sf exchange interaction
Overview
superconductivity and AFM in classic/low-Tc
superconductors (CSC/LTSC)
Summary
anomalous flux penetration into CSC with AFM
ordering
superconductivity and long range magnetism:
introduction, interplay, coexistence
superconductivity and AFM ordering in high-Tc
superconductors (HTSC)
superconductivity and FM ordering in Y9Co7
superconductivity and FM ordering in unconventional
(UCSC) superconductors
Collaborators:
E. Tjukanoff, S. Jaakkola
Wihuri Physical Laboratory, University of Turku, Finland
T. Krzysztoń
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, Poland
Each individual vortex
carries one quantum
of magnetic flux:
0 = (hc/2e)
2.07·10-7 Gcm2
Vortex lattice observed by
STM in NbSe2
H. Hess, R.B. Robinson, and J.V.
Waszczak, Physica B 169 (1991) 422.
Conventional superconductors
Mag
ne
tic f
ield
Temperature
normal
phase
Shub-nikov state,
R = 0 B 0
Meissner state,
R = 0, B = 0
HC1(T)
HC2(T)
Phase diagram of a type II superconductor
nS= ll2
an effective
pinning center
disturbance of II in the size of ~
z y
x
H
Bint
Conventional
superconductors
(low TC)
Structure of an isolated vortex
High-TC
superconductors
Josephson vortices 2D pancake vortices
z
x
y H
two-sublattice AFM with the easy-axis II H
Vortex with magnetic structure
magnetic induction B(r) and magnetic domains around the vortex core
Two-step flux penetration in
AFM superconductor
4M = B - H
T. Krzysztoń, Phys. Lett. 104A, 225 (1984)
DyMo6S8: Hen2 ~ 260 Oe
virgin sample in increasing field at T < TN
at T < TN = 0.4 K:
- H < 200 Oe, superconductivity coexists
with the AFM phase
- H > 200 Oe, superconductivity coexists
with the spinflop (SF) phase
Magnetisation of the DyMo6S8 single crystal (virgin curves) K. Rogacki et al., PRB
64, 94520 (2001)
Phenomenological theory
Free energy of the magnetic superconductor
dvffF MS
B++ 2)4(8
1
superconducting component
42
22
2
12
2++
c
ie
mfS
antiferromagnetic component
) )
+2
1 ,,
22
1
2
21
i zyxj
j
i
i
z
iM MMKJf
coupling between and M
,4 +B +
4),(j
cS
Phenomenological theory (cont.)
Final results: ) )02
2
2
2 enen HBBH +
0
2
2
0
2
ln
)0(2
SF
SF
SFen
B
B
HH
+
ocSF
rKzHH 02
01
22
where:
Experiment versus theory:
T
[K]
Hen2(exp)
[Oe]
Hen2(cal)
[Oe]
0.10 310 265
0.12 290 240
0.14 270 215Conclusion:
The twostep flux penetration can be quantitatively described by
a model in which the electromagnetic interaction is dominant.
ro – the radius of the
spin-flop domain
What more can be obtained from the two-stage
flux penetration process ?
Approach to estimate:
• number of magnetic ions in the vortex core (No)
• superconducting coherence length ()
• London penetration depth ()
• GinzburgLandau parameter () (in magnetic super-
conducting state)
K. Rogacki, et al.,
PRB 64, 094520 (2001)
Free energy of an AFM superconductor:
F(H,T) = Evon + U(n) – BH/4π , Hc1 < H < HSF << Hc2
F(H,T) = (Evo + Eexch)n + U(n) – BH/4π , HSF < H << Hc2
where: Evo selfenergy of the vortex (Hc1 = 4πEv
o/o),
Eexch = (H - HSF) = Noeexch (due to the SF transition in the vortex core)
n vortex density,
U(n) interaction energy between the vortices,
BH/4π field energy (B = no).
Results: T = 0.7 K 0.1 K : (TN = 0.4 K)
• 550 Å const
• 6000 Å 1300 Å
• 11 2.5
What more can be obtained from the two-stage
flux penetration process ?
Conclusions:
• reduction of , observed in the AFM/SF superconducting state,
leads to the strong compression of the quantized flux and results
in a considerable decrease of the GL parameter,
• appearance of the SF phase in the superconducting state (first
in the vortex core) forces the type-II magnetic superconductor to
change towards the ”type-I” superconductor, as predicted by the
theory (M. Tachiki, H. Umezawa, et al., 1983)
Possible explanation:
One reason for the observed “type-II type-I” crossover
could be the attractive force between vortices.
The attractive force between vortices
could be a result of current inversion
in a part of the vortex with the domain
magnetic structure.
The current inversion seems to be the direct consequence
of the quantization of the total flux of a single vortex,
which in a magnetic superconductor is a sum of the spin
and current contribution.
Summary
Classic AFM superconductors
interaction between long-range AFM order and SC order is present
Hc2(T), ac(T), Hc1(T) and
M(H) dependencies reveal
anomalies at TN and HSF
M(H) dependence (with the anomaly) is known
and can be estimated in the AFM-SC state
Hc2(T), Hc1(T) and M(H) dependencies (with the anomaly) are known
nature of the interaction between AFM and SC orders can be analysed
Overview
superconductivity and AFM in classic/low-Tc
superconductors (CSC/LTSC)
Summary
anomalous flux penetration into CSC with AFM
ordering
superconductivity and long range magnetism:
introduction, interplay, coexistence
superconductivity and AFM ordering in high-Tc
superconductors (HTSC)
superconductivity and FM ordering in Y9Co7
superconductivity and FM ordering in unconventional
(UCSC) superconductors
Collaborators:
B. Dabrowski
Physics Department, Northern Illinois University, DeKalb,
Argonne National Laboratory, Argonne, USA
Z. Bukowski, C. Sułkowski
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, Poland
High-Tc AFM superconductors
(4f - 3d4s,2p)
RE TN
[K]
HSF
[kOe]
Nd 0.53 30
Sm 0.61 > 50
Gd 2.24 30
Dy 0.91 10
Er 0.61 8
Yb 0.25 6
Tc 92 K
REBa2Cu3O7-d
Where the interaction between AFM and
superconductivity can be found in RE123 ?
RE TN
[K]
HSF
[kOe]
Nd (s) 0.53 30
Sm (s) 0.61 > 50
Gd (s, ns) 2.24 30
Dy (s) 0.91 10
Er (s) 0.61 8
Yb (s) 0.25 6
REBa2Cu3O7 , TC 92 K
Where the interaction between AFM and
superconductivity can be found in RE123 ?
RE TN
[K]
HSF
[kOe]
Nd (s) 0.53 30
Sm (s) 0.61 > 50
Gd (s, ns) 2.24 30
Dy (s) 0.91 10
Er (s) 0.61 8
Yb (s) 0.25 6
REBa2Cu3O7 , TC 92 K
0.0 0.5 1.0 1.5 2.0 2.5
-1.0
-0.5
0.0
0
5
10
15
20
Gd1.07
Mo6.3
S8
H (kOe)
ac
(a.u
.)
Temperature (K)
0 0.1 0.3
H (kOe)
R (
m
)
0 0.1 0.3 0.6 1.0
R(T), ac(T) – no anomaly at TN
method to decrease TC
and increase TN
chemical substitution
Gd1+xBa2-xCu3O7y
Is it possible to diminish superconductivity and
enhance the AFM interaction in HTSC ?
Gd1.05Ba1.95Cu3O7-y
Gd1.2Ba1.8Cu3O7+y
Searching for the interaction between the
AFM order and superconductivity in:
Gd1.05Ba1.95Cu3O7-y /ox TC = 85 K, TN = 2.26 K
Gd1.05Ba1.95Cu3O7-y /ox
sample annealed in oxygen
(Tc = 85 K, TN = 2.26K)
Gd1.05Ba1.95Cu3O6.3 /Ar
sample annealed in argon
(nonsuperconducting)
Searching for the interaction between the
AFM order and superconductivity in:
Gd1.2Ba1.8Cu3O7+y /ox TC = 42 K, TN = 2.45 K
Gd1.2Ba1.8Cu3O7+y /ox
maximum in ’(T) at T~TN
evidence for
pair breaking
evidence for
interaction between
HTSC and localized AFM
K. Rogacki, PRB 68,
100507(R) (2003)
TC = 42 K, TN = 2.45 K
Maximum in (T) at T TN
- direct evidence for the pair breaking effect
* = (3J2/)∑Φ(q)(q)
enhancement of the spin scattering near the transition to the AFM state is expected and thus an increase of
the pair breaking parameter * at T TN has to appear
J - exchange constant for the interaction s - S
Φ(q) - density of states for the conduction electrons
(q) - magnetic susceptibility (wave-vector dependent)
T TN (for RE123)
(q) wide maximum is expected just above TN
R(TTN) 0 (?), not necessary
BT -T phase diagram
- evidence that the sample is homogeneous
spatial separation of the superconducting and the normal-magnetic phases is excluded
different TN is observed
for superconducting &
non superconducting
samples in B
single maximum is observed at TN for ’(T) dependencies measured in B
Gd1+xBa2-xCu3O7y
ac(T), Hc1(T) i M(H)
were studied for:
Hc1
TN T
M
H
HSF
• DyBa2Cu3O7 (crystals)
• GdBa2Cu3O7 (powder)
ac(T) was studied for:
• Gd1.2Ba1.8Cu3O7 (powder)
Tc = 42 K i TN = 2.45 K
Summary for high-Tc
AFM superconductors
no anomaly for Hc1(T), M(H)
and ac(T) dependencies has been observed at TN and HSF
evidence for the interaction between AFM and SC orders has been found as the pair breaking effect revealed in
ac(T) near TN
High-Tc superconductors – unconventional
layered superconductors cuprates
e.g. Bi2Sr2CaCu2O8
Tc,max= 135 K (HgBa2Ca2Cu3O8)
pnictides
e.g LaFeAsO:F
Tc,max= 55 K
(SmFeAsO:F)
MgB2
Tc,max= 40 K
Mg
B
J.Am.Chem.Soc., 2008
AFM
New class of HTSC: REFeAsO & BaFe2As2
Crystal structure:
(ZrCuSiAs type)
P4/nmm
z = 2
a = 4.035 Å
c = 8.741 Å
alternating layers
of corner shared
FeAs4 & REO4
tetrahedra
Pairing:
spin singlet; extended s-wave, d-wave ? (Knight shift)
high frequency phonon involved (Raman, Infrared)
non-BCS; 2 gaps, 21 3kBTc , 22 8kBTc
(no coherence Hebel-Slichter peak below Tc)
PrFeAsO:F, Tc = 52 K
NdFeAsO:F, Tc = 53 K
SmFeAsO:F, Tc = 55 K
GdFeAsO,Tc = 55 K
Basic properties:
layered, quasi-2D system
large spin fluctuations (m SR)
charge carriers; electrons (RH)
LaFeAsO:
- AFM (TN 140 K, mFe 0.5 mB)
- non-superconducting
doping with 0.05 carriers/Fe
LaFeAsO1-xFx: x = 0.1
- paramagnetic (mFe 0)
- superconducting Tc = 28 K
- Tc ~ ab(0)-2, ab 200 nm,
ab 2 nm, c = ab/c 200
Overview
superconductivity and AFM in classic/low-Tc
superconductors (CSC/LTSC)
Summary
anomalous flux penetration into CSC with AFM
ordering
superconductivity and long range magnetism:
introduction, interplay, coexistence
superconductivity and AFM ordering in high-Tc
superconductors (HTSC)
superconductivity and FM in Y9Co7
superconductivity and FM in unconventional
superconductors
UGe2 ferromagnetic superconductor:
is it really possible to combine water with fire ?
Properties of UGe2:
• TCurie = 52 K, p = 0 Gpa
• Tcmax = 0.6 K, p= 1.25 Gpa
• m = 1.4 mB /U atom
What type of Cooper pairs can be responsible for superconductivity
which coexsists with ferromagnetism ?
Pressure (GPa)
Te
mp
era
ture
(K
)
UGe2
TCurie
10·Tc
S.Saxena et al., Nature 406, 587 (2000)
Important question:
?
Coexistence (cooperation ?) of unconventional
superconductivity and itinerant FM
Why the triplet state ?
• Hex ~ (TCurie/mB) Hp ~ (Tc /mB)
• Hc2 Hp
• IMAG(T) = constant when crossing Tc in H
Te
mp
era
ture
Pressure
Ferromagnetism
UGe2
Tryplet superconductivity (S=1) and itinerant FM coexsist and,
moreover, it appears that they are linked !
Overview
superconductivity and AFM in classic/low-Tc
superconductors (CSC/LTSC)
Summary
anomalous flux penetration into CSC with AFM
ordering
superconductivity and long range magnetism:
introduction, interplay, coexistence
superconductivity and AFM ordering in high-Tc
superconductors (HTSC)
superconductivity and FM in Y9Co7
superconductivity and FM in unconventional
superconductors
Ł. Bochenek, T. Cichorek
Institute of Low Temperature and Structure Research,
Polish Academy of Sciences, Wroclaw, Poland
A. Kołodziejczyk
Faculty of Physics and Applied Computer Science,
AGH, Kraków
Collaborators:
Coexistence of superconductivity and itinerant
ferromagnetism in Y9Co7
Coexistence of superconductivity and itinerant
ferromagnetism in Y9Co7
properties of „old” samples:
• no anomaly in the specific heat Cp(T) dependence
at Tc and TCurie
• low magnetic moment m 0.08 mB/f.u.
superconductivity (Tc 1.5 - 2 K) is present in PM
phase immersed in FM material (TCurie 6 - 8 K) ??
properties of „new” samples:
• clear anomaly in Cp(T) at Tc and TCurie
• low magnetic moment m 0.06 mB/f.u.
• bulk superconductivity (Tc = 2.95 K) present in
FM phase (TCurie = 4.5 K)
-20 0 20 40
-20
0
20
40
0 5 10 15-1.0
-0.5
0.0
0 5 10 15
-25
0
25
50
T = 2 K M (
10
-3 m
B /f
.u.)
B (mT)
Bac
20 mT
100 mT
' a
c (a
rb. u
nits)
T (K)
Y9Co
7
M (
10
-3 m
B /f
.u.)
T (K)
B = 3 mT
ŁB, KR, AK, TC, PRB 91, 235314 (2015); KR, AK, LB, TC, Phil. Mag. 95, 503 (2015)
Coexistence of superconductivity and itinerant
ferromagnetism in Y9Co7
-20 0 20 40
-20
0
20
40
0 5 10 15-1.0
-0.5
0.0
0 5 10 15
-25
0
25
50
T = 2 K M (
10
-3 m
B /f
.u.)
B (mT)
Bac
20 mT
100 mT
' a
c (a
rb. u
nits)
T (K)
Y9Co
7
M (
10
-3 m
B /f
.u.)
T (K)
B = 3 mT
ŁB, KR, AK, TC, PRB 91, 235314 (2015); KR, AK, LB, TC, Phil. Mag. 95, 503 (2015)
-20 -15 -10 -5 0 5 10 15 20
-0.04
-0.02
0.00
0.02
0.04
0 1 2 3 4 5-15
-10
-5
0
5
10
0 50 100 150 2000.00
0.03
0.06
0.09
6 K
M (
em
u/g
)
moH (mT)
2 K
(ZFC)
virgin curves
3 K2.6 K 2.2 K
1.8 K
M (
mem
u/g
)
2 K
100 K
8 K
6 K
2 K
full diamagnetism:
bulk superconductivity
Coexistence of superconductivity and itinerant
ferromagnetism in Y9Co7
2 4 6 80
2
4
6
8
10
0
50
100
150
2000 100 200 300
T (K)
(
m
cm
)
RRR 26
Y9Co
7
Tsc
= 2.95 K
T (K)
(
m
cm
)
ŁB, KR, AK, TC, PRB 91, 235314 (2015); KR, AK, LB, TC, Phil. Mag. 95, 503 (2015)
Coexistence of superconductivity and itinerant
ferromagnetism in Y9Co7
2 4 6 80
2
4
6
8
10
0
50
100
150
2000 100 200 300
T (K)
(
m
cm
)
RRR 26
Y9Co
7
Tsc
= 2.95 K
T (K)
(
m
cm
)
0 1 2 30.0
0.1
0.2
0.3
0.4
0.5
0.6
Y9Co
7
Bc2
(T
)
T (K)
0 2 4
0
4
8
0
0.08
0.20
0.35
0.55
0.70
1.00
B (T)
(
m
cm
)
T (K)
240 Å
l 2 200 Å
„clean-limit”
ŁB, KR, AK, TC, PRB 91, 235314 (2015); KR, AK, LB, TC, Phil. Mag. 95, 503 (2015)
Coexistence of superconductivity and itinerant
ferromagnetism in Y9Co7
0 40 80 120 1600
200
400
50
100
150
200
250
(a)
C /T
(m
J/K
2m
ol)
T 2 (K
2)
= 62 mJK-2
mol-1
D = 228 K
9 T
T +T 3
Y9Co
7
(b)
C /T
(m
J/K
2m
ol)
0 T
0 1 2 3 4 5 6 7 8
60
70
80
(c)
C
/T
(m
J/K
2m
ol)
T (K)
Tsc
2.8 K TC 4.9 K
Coexistence of superconductivity and itinerant
ferromagnetism in Y9Co7
0 40 80 120 1600
200
400
50
100
150
200
250
(a)
C /T
(m
J/K
2m
ol)
T 2 (K
2)
= 62 mJK-2
mol-1
D = 228 K
9 T
T +T 3
Y9Co
7
(b)
C /T
(m
J/K
2m
ol)
0 T
0 1 2 3 4 5 6 7 8
60
70
80
(c)
C
/T
(m
J/K
2m
ol)
T (K)
Tsc
2.8 K TC 4.9 K 0 2 4 6 8 10
0.0
0.2
0.4
0.6
0.8
1.0
Y9Co
7
CT
-1/C
T -
1
T (K)
this work
W. Cheng et al. [21]
10 K
Cpsuper < Cp
normal
increased amount of SC phase
for samples with increased quality
fixed amount of FM phase
SC and FM show bulk
(volume) properties and
coexist in the microscale
Coexistence of superconductivity and itinerant
ferromagnetism in Y9Co7
Overview
superconductivity and AFM in classic/low-Tc
superconductors (CSC/LTSC)
Summary
anomalous flux penetration into CSC with AFM
ordering
superconductivity and long range magnetism:
introduction, interplay, coexistence
superconductivity and AFM ordering in high-Tc
superconductors (HTSC)
superconductivity and FM in Y9Co7
superconductivity and FM in unconventional
superconductors
Collaborators:
E. Tjukanoff, S. Jaakkola
Wihuri Physical Laboratory, University of Turku, Finland
Z. Bukowski, C. Sułkowski, T. Krzysztoń,
Ł. Bochenek, T. Cichorek
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, Poland
B. Dabrowski
Physics Department, Northern Illinois University, DeKalb,
Argonne National Laboratory, Argonne, USA
A. Kołodziejczyk
Faculty of Physics and Applied Computer Science,
AGH, Kraków
Turun yliopisto
University of Turku
Summary:
superconductivity and strong itinerant FM coexist and
it seems that they even cooperate (UGe2, URhGe, UCoGe)
superconductivity and localized AFM coexist and
interact each other (HoNi2B2C, GdBa2Cu3O7)
superconductivity and localized FM don’t want to
coexist – they are enemies (HoMo6S8, ErRh4B4)
superconductivity and weak itinerant FM coexist and
interact each other (Y9Co7)
superconductivity and strong itinerant FM can’t
coexist (Hex Hp) (Fe, REFeAs(O,F))