Interplay between magnetism and superconductivity in EuFe 2-x Co x As 2 studied by 57 Fe and 151 Eu Mössbauer spectroscopy A. Błachowski 1, K. Ruebenbauer.

Prezentacja na temat: "Interplay between magnetism and superconductivity in EuFe 2-x Co x As 2 studied by 57 Fe and 151 Eu Mössbauer spectroscopy A. Błachowski 1, K. Ruebenbauer."— Zapis prezentacji:

1 Interplay between magnetism and superconductivity in EuFe 2-x Co x As 2 studied by 57 Fe and 151 Eu Mössbauer spectroscopy A. Błachowski 1, K. Ruebenbauer 1, J. Żukrowski 2, Z. Bukowski 3, K. Rogacki 3, J. Karpinski 4 1 Mössbauer Spectroscopy Division, Institute of Physics, Pedagogical University, Cracow, Poland 2 Solid State Physics Department, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Cracow, Poland 3 Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wrocław, Poland 4 Laboratory for Solid State Physics, ETH Zürich, Switzerland --------------------------------------------------------------------------------------------------------------------------------------------------------------- XV Krajowa Szkoła Nadprzewodnictwa, Kazimierz Dolny, 9 - 13 października 2011

2 T c max = 56 K 38 K 18 K 15 K Fe-based Superconducting Families pnictogens: P, As, Sb chalcogens: S, Se, Te 1111 122 111 11 LnFeAsO(F) AFe 2 As 2 LiFeAs FeTe(Se,S) Ln = La, Ce, Pr, Nd, Sm, Gd … A = Ca, Sr, Ba, Eu

3 Layered Structure of Fe-based Superconductors --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Parent Compounds Doped Compounds Superconductors Ba 1-x K x Fe 2 As 2 BaFe 2-x Co x As 2 BaFe 2 As 2-x P x Phase Diagram

4 Mössbauer Spectroscopy 1 mm/s 48 neV -ray energy is modulated by the Doppler effect due to the source motion vs. absorber

5 Hyperfine Interactions Isomer Shift Quadrupole Splitting Magnetic Splitting Electron Density Electric Field Gradient Magnetic Hyperfine Field B = 10 T

6 Electric Field Gradient + Magnetic Hyperfine Field = 0° = 90° B = 10 T

7 122 family of Fe-based superconductors

8 BaFe 2 As 2 T SDW = 136 K Ba 0.7 Rb 0.3 Fe 2 As 2 T sc = 37 K 57 Fe Mössbauer spectra NM non-magnetic

9 CaFe 2 As 2 T SDW = 175 K CaFe 1.92 Co 0.08 As 2 T sc = 20 K 57 Fe Mössbauer spectra Relative resistivity (normalized to the resistivity at 300 K) versus temperature

10 Shape of SDW for various temperatures Square root from the mean squared amplitude of SDW versus temperature

11 EuFe 2 As 2 T SDW = 192 K 0 = 0.124 A.Błachowski, K.Ruebenbauer, J.Żukrowski, K.Rogacki, Z.Bukowski, J.Karpinski, PRB 83 134410 (2011) Square root from the mean squared amplitude of SDW versus temperature

12 EuFe 2-x Co x As 2 T N (Eu) = 19 K A.Błachowski, K.Ruebenbauer, J.Żukrowski, Z.Bukowski, K.Rogacki, P.J.W.Moll, J.Karpinski, arXiv:1107.5271

13 EuFe 2-x Co x As 2 57 Fe Mössbauer spectra T SDW = 190 K T SDW = 150 K T SDW = 100 K traces of SDW at 80 K lack of SDW T N (Eu) = 19 K Eu 2+ Transferred Field on 57 Fe

14 EuFe 2-x Co x As 2 57 Fe Mössbauer spectra Shape of SDW

15 EuFe 1.66 Co 0.34 As 2 EuFe 2-x Co x As 2 Square root from the mean squared amplitude of SDW versus temperature

16 EuFe 2-x Co x As 2 151 Eu Mössbauer spectra

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18 Zakład Spektroskopii Mössbauerowskiej Instytut Fizyki Uniwersytet Pedagogiczny ul. Podchorążych 2, 30-084 Kraków www.elektron.up.krakow.pl/ab