Magnetic, thermal and transport behavior in single crystalline RCu2Ge2 (R=La, Ce, Pr and Sm) compounds

Abstract

Magnetic behavior of single crystalline RCu 2 Ge 2 (R=La, Ce, Pr and Sm) compounds is reported. Single crystals were grown using Cu–Ge flux. The compounds crystallize in a tetragonal structure with space group I4/mmm. LaCu 2 Ge 2 shows a diamagnetic behavior. CeCu 2 Ge 2 , PrCu 2 Ge 2 and SmCu 2 Ge 2 orders antiferromagnetically at ≈ 4.2 , 15 and 14.5 K respectively with [001] as the easy axis of magnetization. CeCu 2 Ge 2 shows a Kondo behavior. The Kondo temperature T K , calculated using two different models is of order of 5 K. In PrCu 2 Ge 2 , an additional magnetic transition is observed below 4 K. The origin of the magnetic behavior is attributed to magnetoelastic effects. A possibility of change in easy axis of magnetization after field cycling (below 4 K) is discussed and such effect is rarely observed. The magnetic and specific heat behavior of CeCu 2 Ge 2 and PrCu 2 Ge 2 are analyzed on the basis of crystalline electric field (CEF) model. The CEF splited ground state of rare earth ions is calculated. The magnetic isotherm of SmCu 2 Ge 2 exhibits de Haas-van Alphen oscillations. It is inferred from the frequency spectrum analysis that, the Fermi surface cross-section along [001] is large compared to [100]. • RCu 2 Ge 2 single crystals are grown by self-flux • Anomalous magnetic behavior was observed in PrCu 2 Ge 2 , which was explained on the basis of possible change in the easy axis of magnetization after field cycling. • Crystal electric field calculations were done to explain the observed magnetic properties. • de Haas–van Alphen oscillations were observed in SmCu 2 Ge 2 .