Falkowski M, Strydom A M
Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland. Physics Department, Highly Correlated Matter Research Group, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa.
J Phys Condens Matter. 2017 Oct 4;29(39):395601. doi: 10.1088/1361-648X/aa7e1d. Epub 2017 Jul 6.
The results of the magnetic, electron transport, heat capacity and heat conduction measurements on the new rhombohedral ternary compound PrRhGe have been investigated. The synthesized polycrystalline compound was found to crystallize in the ternary ordered variant of the cubic Laves phase [Formula: see text]-type of structure with the space group R[Formula: see text]m, as previously reported. PrRhGe exhibits a ferromagnetic behaviour below [Formula: see text] K, which was found to be unstable in low applied magnetic fields, revealing characteristics usually attributed to the long-range order. In the entire paramagnetic region electrical resistivity shows monotonous metallic conductivity character. We estimated that the Sommerfeld coefficient γ = 315 mJ/Pr-mol · [Formula: see text] of [Formula: see text] [Formula: see text]Ge is very large with comparison to ordinary metals which indicate the existence of heavy fermion behaviour of itinerant charge carriers at low temperatures or enhanced density of the quasi-particle state at the Fermi level. The crucial role of the crystalline electric field effects on the ground state properties of [Formula: see text] (J = 4) has been also observed. We think that the heavy fermion behaviour in [Formula: see text] [Formula: see text]Ge results from the dynamic low-lying crystal-field fluctuations, since there is no sign of Kondo effect in electrical resistivity and no enhancement of the slope S(T)/T in thermoelectric power data at low temperatures. It suggests that the conduction electrons at the Fermi level does not correlate with the 4f states of [Formula: see text] atoms and hence there is no place for a typical spin Kondo effect, as it is commonly observed in Ce- and Yb-based heavy fermion systems.
对新型菱面体三元化合物PrRhGe进行了磁性、电子输运、热容量和热传导测量,并对结果进行了研究。如先前报道,合成的多晶化合物结晶为立方Laves相[化学式:见正文]-型结构的三元有序变体,空间群为R[化学式:见正文]m。PrRhGe在[化学式:见正文]K以下表现出铁磁行为,发现在低外加磁场中不稳定,揭示了通常归因于长程有序的特性。在整个顺磁区域,电阻率显示出单调的金属导电特性。我们估计,与普通金属相比,[化学式:见正文][化学式:见正文]Ge的索末菲系数γ = 315 mJ/Pr-mol·[化学式:见正文]非常大,这表明在低温下巡游电荷载流子存在重费米子行为,或者费米能级处的准粒子态密度增加。还观察到了晶体电场效应在[化学式:见正文](J = 4)基态性质上的关键作用。我们认为,[化学式:见正文][化学式:见正文]Ge中的重费米子行为源于动态的低能晶体场涨落,因为在电阻率中没有近藤效应的迹象,并且在低温下热电功率数据中斜率S(T)/T也没有增强。这表明费米能级处的传导电子与[化学式:见正文]原子的4f态不相关,因此不存在典型的自旋近藤效应,这在基于Ce和Yb的重费米子系统中是常见的。