Magnetic anisotropy and ferromagnetic correlations above the Curie temperature in Eu2CuSi3 single crystals

作者：Cao, C. D.^*; Klingeler, R.; Vinzelberg, H.; Leps, N.; Loeser, W.; Behr, G.; Muranyi, F.; Kataev, V.; Buechner, B.

来源：Physical Review B, 2010, 82(13): 134446.

DOI：10.1103/PhysRevB.82.134446

• LARGE NEGATIVE MAGNETORESISTANCE
• ELECTRON-SPIN RESONANCE
• INTERMETALLIC COMPOUNDS
• BEHAVIOR
• GD2PDSI3
• GROWTH
• SILICIDES
• METALS
• TB
• ER

Magnetization M(T,B), specific heat c(p)(T), and electrical resistivity rho(T,B) show ferromagnetic ordering in Eu2CuSi3 single crystals below the Curie temperature T-C=34 K. Temperature T and magnetic field B-dependent M(T,B) data give evidence for a sizable magnetic anisotropy in the AlB2-derived hexagonal structure at T < T-C. The increase in vertical bar dM/dT vertical bar at T-C for B=50 mT along the easy magnetic c axis (< 001 >) is more than twice as large as for B along the a axis (< 001 >). The analysis of c(p)(T) in the magnetically ordered phase reveals signatures of a spin- reorientation process at T approximate to 10 K below which the magnetic anisotropy in M(T,B) almost vanishes. Measurements of electron-spin resonance (ESR) on Eu2+ ions reveal the anisotropy of the resonance field and the additional narrowing of the ESR signal at T<100 K that prove appreciable short- range ferromagnetic correlations far above T-C. These lead to a large negative magnetoresistance observed in the rho(T,B) measurements even up to a temperature T approximate to 100 K. Below 50 K the ESR line starts to split due to the emergence of two magnetically nonequivalent Eu sites. The onset of magnetic order is manifested in the ESR spectrum by nucleation of a third line. Below T approximate to 10 K, where thermodynamic data suggest a transformation of the ordered spins to a state with strongly reduced anisotropy, the ESR spectrum evolves into a featureless broad asymmetric peak.

• 出版日期2010-10-27
• 单位西北工业大学