Investigation of magnetic order inSmTr2Zn20 (Tr=Fe,

D. Yazici

¹

,

B. D. White

²

,

P. C. Ho

³

et al.

Abstract

Single crystals of the "cage compounds" SmTr2Zn20 (Tr = Fe, Co, Ru) and SmTr2Cd20 (Tr = Ni, Pd) have been investigated by means of electrical resistivity, magnetization, and specific heat measurements. The compounds SmFe2Zn20, SmRu2Zn20, and SmNi2Cd20 exhibit ferromagnetic order with Curie temperatures of TC = 47.4 K, 7.6 K, and 7.5 K, respectively, whereas SmPd2Cd20 is an antiferromagnet with a Néel temperature of TN = 3.4 K. No evidence for magnetic order is observed in SmCo2Zn20 down to 110 mK. The Sommerfeld coefficients γ are found to be 57 mJ/mol-K 2 for SmFe2Zn20, 79.5 mJ/mol-K 2 for SmCo2Zn20, 258 mJ/mol-K 2 for SmRu2Zn20, 165 mJ/mol-K 2 for SmNi2Cd20, and 208 mJ/mol-K 2 for SmPd2Cd20. Enhanced values of γ and a quadratic temperature dependence of the electrical resistivity at low temperature for SmRu2Zn20 and SmPd2Cd20 suggest an enhancement of the quasiparticle masses due to hybridization between localized 4f and conduction electron states.

Low Curie temperature ferromagnetic phase in SmPt2Cd20 possibly accompanied by strong quantum fluctuations

“…This is in good agreement with the similar trend observed in SmTr 2 X 20 with X = Zn and Cd [15,[25][26][27], in marked contrast with strongly-hybridized characters in X = Al compounds, e.g., mixed valent Sm ion state and − log T behavior in ρ(T ) [19][20][21][22][23].…”

“…The lattice parameter a = 15.6237(15)Å was found to be the largest among the SmTr 2 X 20 family [15,30]. The large atomic displacement parameter B eq of Cd (3) at the 16c site is a common feature in RT r 2 X 20 [12,14,21,30].…”

“…RTr 2 X 20 compounds have gathered much interest in recent years because of a wide variety of strongly correlated electron behaviors [15][16][17][18]. In SmTr 2 Al 20 (Tr = Ti, V, Cr, and Ta), c-f hybridization is relatively strong.…”

“…For C el + C ph , the data of a nonmagnetic reference compound LaNi 2 Cd 20 are used (≃ γT + βT 3 with γ = 25.9 mJ/mol K 2 and β = 4.56 mJ/mol K 4 below 2 K) [15]. The extracted C 4f /T and the magnetic contribution to the entropy S 4f (T ) = Fig.…”

Nonmagnetic ground state in the cubic compoundsPrNi2Cd20andPrPd2Cd20

“…27 Systematic studies of the structural, magnetic, electrical transport, and thermodynamic properties of the RM 2 Cd 20 family were recently published. 27,28 Since all of the known PrM 2 X 20 (X = Al, Zn) compounds are heavy fermion materials, [17][18][19][20][21][22][23][24][25] we were motivated to study these X = Cd compounds to ascertain whether they also exhibit strong electronic correlations or multipolar order.…”