3rd-14th September 2018 EASIschool in Vienna

UNIVERSITÀ DEGLI STUDI DI GENOVA

Marie Sklodowska-Curie Action (MSCA) Innovative Training Networks (ITN)H2020 FP grant agreement no. 764879

Iron-based and MgB2 classes of superconductors

Part II - IBS

The lecture will review:1) the basic properties of IBS , including the

interplay between superconductivity and AFM, unconventional pairing;

2) the superconducting properties, including the upper critical field Hc2 , critical current density Jc and critical parameters;

3) the development and fabrication of wiresand tapes.

2014

100 KFeSe

Single layer

58 K

112 type (CaFeAs2)

Intercalated FeSe-11122 ( KFe2Se2)

REFeAsO1111

Tc,max = 58 K

AEFe2As2122

Tc,max = 40 K

Fe(Se,Te)11

Tc,max = 21 K

Superconductivity occurs uponsubstituting O with F, HDeficency of O heterovalent REFe with Coheterovalent AE metalexternal pressureinternal pressuresubstitution of Te with Se, Sexternal pressure

M1-xAExFe2-yTMyAs2-zPz

RE=La, Ce, Pr 40 -46

Tc is higher in the order 1111 > 122 > 11. Does interlayer spacing of FeAs layers enhance optimal Tc ?

anionheightFe

Pn, Ch

Phenomenological correlationof Tc with the tethraedron angle and with the anion hight

Anion hight is a structural parameter associated with strength of spin fluctuation

H.Hosono, et al., Mater. Today 21 (2018) 278.

RE

OF

AsFe

LaFeAsO1-xFx

LaFeAsO1-xFx

S. Sanna et al., PRB 80, 052503 (2009).A. Martinelli et al PRL 106, 227001 (2011)

SmFeAsO1-xFx

FeTe

FeSe

0 50 100 150 200 2500

2

4

6

resis

tivity

[mΩ

cm

]

Temperature [K]

LaFeAsOC. de la Cruz et al., 2008 Nature 453 899

a SDW ordering of Fe (≈0.4µB/Fe ) associated to a tetragonal-orthorhombic transition

0 50 100 150 200 250 3000.0

0.5

1.0

1.5

ρ (m

Ω c

m)

T (K)

FeTe

FeTe exhibits:bicollinear AFM ordering of Fe (≈2.5 µB/Fe ) spin direction 45° rotated in

respect to 1111 and 122Tetragonal to monoclinic transition

11 1111-

Igor I. Mazin, Nature 464 (2011) 183D. J. Singh and M.-H. Du: Phys. Rev. Lett. 100 (2008)

Superconducting order parameter: MgB2 : two-band s wave with the same sign IBS : two-band s± wave

MgB2 IBS

Q

holes

electrons

0.1 1 100.0

0.2

0.4

0.6

0.8

1.0

V3Si

MgB2

Nd-1111

T c/Tc0

g=Γ/2πkBTc0

YBCO

C Tarantini et al.,PRL 104, 087002 (2010)

S Onari eta l., PRL 103, 177001 (2009)]

In case of s ± wave pairing a rapidsuppression of Tc with impuritieshas been predicted

Superconductivity in IBS isquite robust agains disorder

I. Pallecchi et al., SUST 31, 034007 (2018)

0.0 0.5 1.0 1.5

0.4

0.6

0.8

1.0

T c/Tc0

g

1111

122

The lecture will review:1) the basic properties of IBS , including the

interplay between superconductivity and AFM, and unconventional pairing;

2) the superconducting properties, including the upper critical field Hc2 , the critical current density Jc and the critical parameters;

3) the development and fabrication of wires and tapes.

Putti et al. SUST 23 034003 (2010)

Slope -15 T/K Anisotropy is 5

30 35 40 45 500

10

20

30

40

50

60 H//ab H//c

µ 0H

c2 [T

]

T [K]

NdFeAs(OF)

8 12 16 20

T [K]

Ba(FeCo)2As2

Slope -4.9 T/K Anisotropy is 2-1.5

0 5 10 15 20

T [ K ]

Fe(TeSe)

Slope -50 T/K Anisotropy 3-1

1111 11

C. Tarantini et al., PRB 84, 184522 (2011)

11

1111

1111 122 11 YBCO MgB2

Tc [K] 55 38 16 93 39

Bc2 (0) [T] >50 60 55 >50 20-30

ξab [nm] 2.5 3 1.5 2.2 10

γΗ 5 2 2-3 4-14 3-5

λab (nm) 200 200 490 180 50-100

Ginzburg number Gi

4·10-4 2·10-5 1·10-3 >10-3 <10-5

pairing Not BCS Not BCS Not BCS Not BCS BCS

Several similarities with HTS : High Hc2, small coherence length, unconventional pairingbut, lower anisotropy

𝐺𝐺𝑖𝑖 = ~ ∆𝑇𝑇𝑇𝑇𝑐𝑐

Width of the critical regime around Tc

H.Sato, et al., APL 104, 182603 (2014)

Jc @ low temperature is:

Large (above 106 A/cm2 in

self-field)

Almost field independent

@ 5 K

Jc @ low temperature is:

Large (above 106 A/cm2 in

self-field)

Almost field independent

Nearly isotropic

Field independentCritical current density:

Jc is almost isotropic with increasing

both the temperature and the

magnetic field.

Jc remains above 105 A/cm2 @0.8 Tc

Pinning by point defects

P. Yuan et al., SUST 29 (2016) 035013

Tc= 18 K

Kurth et al., EUCAS 2015Iida , Sci. Rep. 3:2139 (2013)Tarantini et al., Sci. Rep. 4, (2014).Sato et al., Applied Physics Letters 104, 182603 (2014)Si, W. et al. Nat. Commun. 4:1347 (2013).

0 10 20 30 40 501

10

100

1000

F p , G

N/m

3

B , Tesla

Nd-1111 (Kurth et al.) Sm-1111 (Iida et al.) 122 (Tarantini et al.) 11 (Si et al.)

YBCO 2G H//c

NbSn3

Filled symbols: H//abEmpty symbols: H//c

400 GN/m3

0 5 10 15 20 25 30 35 40 45 5010-3

10-2

10-1

100

our data W. Si et al., APL 106 2015

J cGB/J

cG

misorientation angle

Also in IBS Jc is suppressed by misaglinedgrains

In HTS 𝜽𝜽𝑪𝑪~𝟒𝟒° In IBS 𝜽𝜽𝑪𝑪~𝟏𝟏𝟏𝟏𝟏 IBS has Advantageous GBs over HTS

0 10 20 30 40

104

105

106

107

J GB (

A/cm

2 )

Θ (°)

YBCO

0 10 20 30 40

104

105

106

107

11 (Si et al. 2015)11 (Kawale et al. 2014)

Co doped 122 (Lee et al. 2009)

P doped 122 (Ikuta et al. 2013)

J GB [A

/cm

2 ]

θ [deg]

Co doped 122 (Katase et al.2011)YBCO

Kawale et al.,ASC 2014Si et al, Appl. Phys. Lett. 106 032602 (2015)11 bicrystals

122 bicrystalsLee et al., Appl. Phys. Lett. 95, 212505 (2009).Katase et al., Nat. Commun. 2, 409 (2011)Sagakami et al.,Physica C 494 (2013) 181–184

11 bicrystals

122 bicrystals

The lecture will review:1) the basic properties of IBS , including the interplay

between superconductivity and AFM, unconventional pairing;

2) the superconducting properties, including the upper critical field Hc2 , the critical current density Jc and the critical parameters;

3) the development and fabrication of wires and tapes.

DyBa2Cu3O7-y polycrystal SmFeAsO0.85 polycrystal

Seuntjens et al., JAP. 67, 2007 (1990) Yamamoto et al., SUST 21, 095008 (2008)

4.2 K

Intragrain Jc Jc Intragrain Jc

H.Hosono, et al., Mater. Today 21 (2018) 278.

Best performaces for the 122 family

Jc rather flat and in the best samples close to 105 A/cm2

above 10 T

Main technologies for ReBCO-CC manufacturing

The goal: to achieve highly in-plane oriented practical metal-tape substrates.

Si W. et al, Nat. Comm 4 (2013) 1347

Si W. et al, APL98 (2011) 262509

Excellent results obtained on 11 thin

films growth on IBAD and RABiTS

Jc>𝟏𝟏𝟏𝟏𝟓𝟓𝑨𝑨/𝒄𝒄𝒄𝒄𝟐𝟐 @ 35 T on RABiTS

Jc>𝟏𝟏𝟏𝟏𝟓𝟓𝑨𝑨/𝒄𝒄𝒄𝒄𝟐𝟐 @ 9 T on IBAD-LMO

with in-plane misaglinment ∆𝝓𝝓 ∼7.7°

Xu Z. et al., SUST 30 (2017) 035003

IBAD-LMO

K. Iida et al., Sci. Rep. 7 (2017) 39951.

IBAD-MgO

H. Sato et al., Sci. Rep. 6 (2016) 36828

2010 2012 2014 2016 2018101

102

103

104

105

106

J c [

A/cm

2 ]

Year

PIT CC 1111PIT CC 122PIT CC 11

T= 4.2Kself-field

I. Pallecchi, M. Eisterer, A. Malagoli, M. Putti, SUST (2015) 28

Coated Conductors

PIT Wires& Tapes

2010 2012 2014 2016 2018100

101

102

103

104

105

106

J c (A/

cm2 )

Year

1111 122 11@ B= 10 T

Practicalapplication

Jc anisotropyAwaji EUCAS2015

Courtesy: Y.Ma CAS

Effect of strain

H.Hosono, et al., Mater. Today 21 (2018) 278.

Cross-section of 114 multi filamentary 122 wires&tapes

The first 100-m-class 122 wire

H.Hosono, et al., Mater. Today 21 (2018) 278.

Qingjin XU” Status of high field magnet technology for CEPC-SPPC” 2017 FCC Week 29 May-2 June 2017 Berlin, Germany

Advantages

High field superconductors

Isotropic Jc

Effective pinning mechanisms

Suitable for fabrication with

cheap method

DisadvantagesModerate Tc

Hazardous material

Technology too young

H.Hosono, et al., Mater. Today 21 (2018) 278.