Interplay between Kondo-like behavior and short-range antiferromagnetism inEuCu2Si2single crystals

Abstract

The static and dynamic magnetic properties, electrical resistivity, specific heat, and magnetoresistance have been studied in EuCu 2 Si 2 single crystals grown by a floating zone method. The magnetic susceptibility exhibits a considerable anisotropy and a steep rise below 10 K for external fields parallel to the c axis but with no evident magnetic ordering in the temperature range of 2-350 K. The data imply a gradual change in the Eu valence as a function of temperature. Electron spin resonance ͑ESR͒ measurements reveal a sizeable fraction of stable Eu 2+ magnetic moments that interact with conduction electrons and develop quasistatic antiferromagnetic correlations on the ESR timescale. The electrical resistivity and specific heat demonstrate the presence of spin fluctuations and Kondo-like behavior, which apparently competes with the antiferromagnetic order. The analysis of experimental data enables to conclude that the remarkable diversity of the physical properties of EuCu 2 Si 2 results from the variation of lattice parameters as well as of local crystal chemistry as a consequence of the particular preparation route employed for the growth of single crystals and polycrystals.

Magnetic ordering and dense Kondo behavior inEuFe2P2

“…The observed dense Kondo behavior in EuFe 2 P 2 could be attributed to the proximity of the 4f level to Fermi energy. [5] To our knowledge, dense Kondo behavior in Eu-containing compounds is rarely discovered, [38] primarily because Eu 2+ carries a large moment. Kondo effect involves the intrasite coupling between local moment and conduction carriers, while the RKKY interaction is a long-range intersite magnetic exchange through conduction carriers.…”

Self-flux growth of large EuCu2Si2 single crystals

“…Different from indium flux grown single crystals, the inverse susceptibility w À 1 (T) does not show a linear Curie-Weiss law in the range from 2 K to room temperature [10]. This behavior reflects the well-known valence fluctuations in this compound [3,4], which was also observed for other Eu-containing compounds [14].…”

“…The latter observation implies a stable Eu 2 + state in that compound. The distinct susceptibility behavior of the FZ and indium flux grown single crystals also demonstrates different valence features of Eu ions in the two cases [10].…”

“…Here the molten zone acts as a self-flux, which considerably differs from the In flux used by previous authors [7,8]. The magnetic and electronic transport properties of the grown crystals have been described in a previous article [10]. Here we analyze differences between the single crystals with respect to dissimilar preparation routes.…”

Single crystal growth of Eu2CuSi3 intermetallic compound by the floating-zone method

“…However, crystal growth has so far been hampered by the volatile character of Eu. The applicability of floating-zone melting under elevated Ar pressure for crystal growth of the compound EuCu 2 Si 2 with relatively low melting temperature (1255 1C) was demonstrated only recently [15,16].…”