Neutron diffraction study of the U(Pd1-xFex)2Ge2 magnetic structureстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The neutron diffraction and magnetic susceptibility studies have shown that the magnetic structure of UPd2Ge2 changes dramatically even under very low iron doping. Though the general magnetic structure of pure UPd2Ge2 and of 1%Fe-doped samples is the same, the temperature intervals of existence of different magnetic phases are different. The values of transition temperatures, where (i) the `square’ modulated longitudinal spin-density wave (LSDW) structure with the propagation vector k=(0; 0; kz=34) starts to transform into the sinusoidal modulated LSDW structure and (ii) the commensurate phase transforms into incommensurate one, shift under the 1%Fe doping to the higher temperatures (from 50 to 65 K and from 80 to 90 K, respectively). In the pure and 1%Fe-doped UPd2Ge2, the magnetic transition from the commensurate to incommensurate phase is accompanied by the drastic decrease of the propagation vector kz. In the 2%Fe-doped sample, besides the Néel point of TN=135 K, we have found two additional characteristic temperatures of 65 and 93 K. Below 65 K, the material has a simple antiferromagnetic (AF) structure with the propagation vector k=(0; 0; 1) and, at 65 K<T<TN, the magnetic structure is LSDW with sinusoidal modulation. Over almost the total region 65 K<T<TN, the LSDW magnetic structure is incommensurate. Only at about 93 K, the propagation vector passes the commensurate value of 34, whereas kz>34 at 65<T<93 K and kz<34 at 93 K<T<TN. We have found that the magnetic susceptibility and the uranium magnetic moment are sensitive to the kz>34⇒kz<34 transition. With increasing iron concentration to x⩾0.15, the simple AF structure with k=(0; 0; 1) develops over all temperature region up to the Néel point. Below TN, the uranium magnetic moments are always parallel to the tetragonal c-axis.