Shape of spin density wave versus temperature in AFe2As2(A = Ca, Ba, Eu): A Mössbauer study

作     者：A. Błachowski K. Ruebenbauer J. Żukrowski K. Rogacki Z. Bukowski J. Karpinski 

作者机构：Mössbauer Spectroscopy Division Institute of Physics Pedagogical University PL-30-084 Kraków ul. Podchorążych 2 Poland Solid State Physics Department Faculty of Physics and Applied Computer Science AGH University of Science and TechnologyPL-30-059 Kraków Al. Mickiewicza 30 Poland Institute of Low Temperatures and Structure Research Polish Academy of Sciences PL-50-422 Wrocław ul. Okólna 2 Poland Laboratory for Solid State Physics ETH Zurich CH-8093 Zurich Switzerland 

出 版 物：《Physical Review B》 (Phys. Rev. B Condens. Matter Mater. Phys.)

年 卷 期：2011年第83卷第13期

页      面：134410-134410页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

主　　题：DENSITY wave theory SUPERCONDUCTORS MOSSBAUER spectroscopy ELECTRON paramagnetic resonance ANTIFERROMAGNETISM 

摘      要：Parent compounds AFe2As2 (A = Ca, Ba, Eu) of the 122 family of the iron-based superconductors have been studied by Fe57 Mössbauer spectroscopy in the temperature range 4.2–∼300 K. Spin density waves (SDW) have been found with some confidence. They are either incommensurate with the lattice period or the ratio of the respective periods is far away from the ratio of small integers. SDW shape is very unconventional (i.e., differs from the sinusoidal shape). Magnetic order starts with lowered temperature as narrow sheets of the significant electron spin density separated by areas with very small spin density. Magnetic sheets are likely to be ordered in the alternate antiferromagnetic fashion as the material as a whole behaves similarly to the collinear antiferromagnet. A further lowering of temperature simply expands sheet thickness leading to the near triangular SDW. Finally, sheets fill the whole available space and the almost rectangular shape of the SDW is reached. The substantial maximum amplitude of SDW appears at the temperature just below the magnetic onset temperature, and this maximum amplitude increases slightly with lowering temperature. The square root from the mean squared hyperfine field behaves versus temperature according to the universality class (1,2) (i.e., with the electronic spin space having dimensionality equal to unity and the real space having dimensionality equal to 2). The more or less pronounced tail above transition temperature due to the development of incoherent SDW is seen.