Resistivity studies in magnetic materials. Makariy A. Tanatar

Transcription

1 Resistivity studies in magnetic materials 590B Makariy A. Tanatar November 30, 2018 Classical examples Quantum criticality Nematicity

2 Density waves: nesting

3 Classics: resistivity anomaly at ferromagnetic transition Resistivity of FM Ni Tc=617 K Link between d /dt and C(T)

4 Classics: resistivity at antiferromagnetic transition Resistivity of AFM -Mn Resistivity of SDW Cr T N ~100K

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6 Gd ferromagnetic Lu non-magnetic

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8 T N =66.5K Incommensurate Helix k= (0, 0, l) 15K l = close to 6/7 (1/0.857) 64K l = close to 5/6 (1/0.833)

9 EuCo 2 P 2 : In-plane resistivity 1.00 a / a (300K) *[ a / a (300K)] J M.E.Fisher & J.S.Langer, PRL 1968 Ferromagnetic ordering Q=0 T (K) 0

10 C mag (J/mole K) a ( cm) S mag (J/mole K) T h T(K) T (K)

11 EuCo 2 P 2 : In-plane vs. inter-plane resistivity J 1.0 T N T C-I / (300K) 0.5 c a T(K) Fermi surface folding by Qc partial gaps

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13 CeIn 3 Ce In Simple AF Q [111] magnetism superconductivity non-fermi liquid properties N. D. Mathur et al., Nature 394, 39 (1998)

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15 T 2 coefficient Diverging T 2 coefficient Divergent m* Magnetic field tuning T 2 coefficient

16 Temperature 3D Magnetically mediated superconductivity 2D CeIn 3 (T)~T 1.33 (T)~T 2 m a g n e t i s m insulator High-T c cuprates PG S/C (T)~T (T)~T 2 metal Quantum fluctuations of OP at QCP as a SC glue Fluctuations give unusual (T)~AT n with n 2 The range of FL behavior TFL 0 at QCP Diverging effective mass at QCP N.D.Mathur et al. Nature 394, 39 (1998) Electron concentration PG and SC same anisotropy

17 [001] CeMIn 5 magnetism, QCP & superconductivity Perfect compounds for studying relation between QCP and SC P.G.Pagliuso et al. (2002) [001] [100] [100] HTSC AFM LTSC J. Paglione et al., PRL 91, (2003) A. Bianchi et al., PRL 91, (2003) AT 2, A~(H-Hc) FL H QCP not inside the SC dome but at its boundary H c ~ H c2

18 Resistivity at magnetic transitions: CeRhIn 5 Total (thermal) resistivity, including small angle scattering, is directly proportional to magnetic entropy J.Paglione et al. PRL 94, (2005)

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21 CeCoIn 5 unusual anisotropic QCP M.A. Tanatar, J. P. et al. Science (2007) Unusual features: QCP not inside SC dome, but at the boundary Very pronounced NFL behavior for one direction of transport, WF law violation Unusual exponents in transport, ρ, w and δ all linear in T Anisotropy of the characteristic energy scale: 5 K in-plane transport, ~0K inter-plane transport

22 CeCoIn 5 H summary In-plane H J Inter-plane J Anisotropic quantum criticality Anisotropic spin fluctuation spectrum

23 Anisotropic resistivity in paramagnetic state of CeCoIn 5 M.A.Tanatar et al. Science 312, 1320 (2007) T. Park Nature 456, 366 (2008) Speculations: spins in-plane (Rh) vs spin along c-axis (Co)

24 Cuprates 2D single band ES 2D magnetism Iron arsenides 5 band FS 2D? 3D magnetism Pseudogap d-wave Repeating theme of Superconductivity emerging from magnetic order s wave I.I.Mazin, Nature 464, 183 (2010)

25 S. Kasahara et al PRB81, (2010) BaFe 2 (As 1-x P x ) 2

26 Most clear example BaFe 2 (As 1-x P x ) 2 Y. Nakai et al. PRL 105, (2010)

27 c / c (300 K) x= T[K]

28 Quantum criticality in iron-based superconductors (T)~T 2 T TO, T N (cp) 0 Quantum Critical Point Tc maximum : quantum fluctuations as a SC glue Non-Fermi-liquid (T)~AT n with n 2 The range of FL behavior T FL 0 at QCP 2.0 x= N. Doyron-Leyraud, PRB80, (2009) L.Taillefer Ann. Rev. Cond.Matter Physics 1, 51 (2010) Layered BaCo122: map of in-plane resistivity Vs. control parameter a / a (300K) x= Co-doping T [K]

29 D. K. Pratt et al. PRL2009 Tetragonal phase of iron arsenides intrinsically unstable to orthorhombic distortion with magnetic stripe formatio Coinciding-to-Split transitions Formation of structural domains

30 Ca Ba Sr 100 µm Terrace on crystal surface February 19, 2009 Low-temperature polarized light images of AFe2As2 M. A. Tanatar et al. PRB79, (R) (2009)

31 CaFe 2 As 2 Detwinning through potential contacts cycled ->

32 b a Ba(Fe 1-x Co x ) 2 As 2 In all compositions a < a Juin-Haw Chu et al. Science

33 (Ba 1-x K x )Fe 2 As 2 E.C. Blomberg et al. arxiv:

34 R.M.Fernandes, A.V.Chubukov, Y.Schmalian Nature Physics 10, (2014))

35 Ba122 at optimal doping Big question: why are they different? BaCo BaK BaP c c / (300K) 0.5 a / (300K) 0.5 a / (300 K) 0.5 a c BaCo122 x= T [K] a ~ T-linear c T-linear T<T PG BaK122 x= T[K] a PG c PG BaP122 x= a T-linear c T-linear

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43 Magnetically mediated superconductivity Phase diagram as map of resistivity (T)~T 2 T N (cp) 0 Quantum Critical Point Tc maximum : quantum fluctuations as a SC glue Non-Fermi-liquid (T)~AT n with n 2 The range of FL behavior T FL 0 at QCP Layered BaCo122: map of in-plane resistivity N. Doyron-Leyraud, PRB80, (2009) L.Taillefer Ann. Rev. Cond.Matter Physics 1, 51 (2010) Directional view of phase diagram