Magnetyzm i nadprzewodnictwo w EuFe2-xCoxAs2 – badania metodą spektroskopii mössbauerowskiej 57Fe i 151Eu A. Błachowski1, K. Ruebenbauer1, J. Żukrowski2, Z. Bukowski3, K. Rogacki3, P.J.W. Moll4, J. Karpinski4, M. Matusiak3 1Laboratorium Spektroskopii Mössbauerowskiej, Uniwersytet Pedagogiczny, Kraków, Polska 2Katedra Fizyki Ciała Stałego, Wydział Fizyki i Informatyki Stosowanej, Akademia Górniczo-Hutnicza, Kraków, Polska 3Instytut Niskich Temperatur i Badań Strukturalnych PAN, Wrocław, Polska 4Laboratory for Solid State Physics, ETH Zurich, Switzerland --------------------------------------------------------------------------------------------------------------------------------------------------------------- IX Ogólnopolskie Seminarium Spektroskopii Mössbauerowskiej OSSM’2012, Lublin - Kazimierz Dolny, 10-13 czerwca 2012

Fe-based Superconducting Families pnictogens: P, As, Sb chalcogens: S, Se, Te 1111 122 111 11 LnFeAsO(F) AFe2As2 LiFeAs FeTe(Se,S) Ln = La, Ce, Pr, Nd, Sm, Gd … A = Ca, Sr, Ba, Eu Tc max = 56 K 38 K 18 K 15 K

Layered Structure of Fe-based Superconductors --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Phase Diagram Ba1-xKxFe2As2 BaFe2-xCoxAs2 BaFe2As2-xPx Parent Compounds Doped Compounds ↓ Superconductors

”122” family of Fe-based superconductors

(normalized to the resistivity at 300 K) 57Fe Mössbauer spectra CaFe2As2 TSDW = 175 K CaFe1.92Co0.08As2 Tsc = 20 K Relative resistivity (normalized to the resistivity at 300 K) versus temperature A.Błachowski, K.Ruebenbauer, J.Żukrowski, Z.Bukowski, M.Matusiak, J.Karpinski, Acta Physica Polonica A 121, 726 (2012)

57Fe Mössbauer spectra Ba0.7Rb0.3Fe2As2 Tsc = 37 K BaFe2As2 TSDW = 136 K Ba0.7Rb0.3Fe2As2 Tsc = 37 K NM non-magnetic

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

Square root from the mean squared amplitude of SDW EuFe2As2 Square root from the mean squared amplitude of SDW versus temperature TSDW = 192 K 0 = 0.124 A.Błachowski, K.Ruebenbauer, J.Żukrowski, K.Rogacki, Z.Bukowski, J.Karpinski, Phys. Rev. B 83, 134410 (2011)

EuFe2-xCoxAs2 TN (Eu) = 19 K Phys. Rev. B 84, 174503 (2011) A.Błachowski, K.Ruebenbauer, J.Żukrowski, Z.Bukowski, K.Rogacki, P.J.W.Moll, J.Karpinski, Phys. Rev. B 84, 174503 (2011)

EuFe2-xCoxAs2 57Fe Mössbauer spectra Eu2+ Transferred Field on 57Fe TN (Eu) = 19 K TSDW = 190 K TSDW = 150 K TSDW = 100 K traces of SDW at 80 K lack of SDW Eu2+ Transferred Field on 57Fe

EuFe2-xCoxAs2 57Fe Mössbauer spectra Shape of SDW

Square root from the mean squared amplitude of SDW EuFe1.66Co0.34As2 Square root from the mean squared amplitude of SDW versus temperature EuFe2-xCoxAs2

151Eu Mössbauer spectroscopy

EuFe2-xCoxAs2 151Eu Mössbauer spectra