Solid State Sciences 8 (2006) 548–555 www.elsevier.com/locate/ssscie Magnetic properties and 155 Gd Mössbauer spectroscopy of LT-GdNiIn 2 Kazimierz L ˛ atka a , Roman Kmie´ c b , Andrzej W. Pacyna b , Jacek Gurgul c , Vasyl’ I. Zaremba d,e , Rainer Pöttgen e,∗ a Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków, Poland b Henryk Niewodnicza´ nski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland c Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Kraków, Poland d Inorganic Chemistry Department, Ivan Franko National University, Kyryla and Mephodiya Street 6, 79005 Lviv, Ukraine e Institut für Anorganische und Analytische Chemie,Universität Münster, Corrensstrasse 36, D-48149 Münster, Germany Received 28 September 2005; accepted 8 November 2005 Available online 27 January 2006 Abstract A polycrystalline, single phase sample of the low-temperature (LT) modification of GdNiIn 2 (MgCuAl 2 type, Cmcm, a = 434.5(1), b = 1047.6(3), c = 731.8(2) pm) was synthesized by arc-melting of the elements and subsequent annealing of the sample at 870 K. The magnetic properties of this compound were studied thoroughly by AC and DC magnetic susceptibility measurements and 155 Gd Mössbauer spectroscopy. These results reveal four phase transitions: from a para- to a ferromagnetic state at T C = 60.5(5) and three other transitions at T 1 = 19.4(2) K, T 2 = 12.2(2) K, and T 3 = 4.0(2) K, respectively, which can be tentatively described as spin-reorientation transitions. LT-GdNiIn 2 shows strong thermal irreversibility between zero field cooled (ZFC) and field cooled (FC) DC magnetization.  2006 Elsevier SAS. All rights reserved. Keywords: Intermetallic compound; Magnetism; Mössbauer spectroscopy 1. Introduction Intermetallics with the orthorhombic MgCuAl 2 type struc- ture [1] have intensively been studied with respect to their peculiarities in chemical bonding and their interesting physi- cal properties. An overview is given in a recent review arti- cle [2]. Although more than 100 MgCuAl 2 type compounds have structurally been characterized, only few of them have been studied with respect to their physical properties. So far, in the RENiIn 2 (RE = Y, Ce, Pr, Nd, Sm, Eu, Gd, Yb) [3–9] series, only the magnetic behaviour of the 3.4(3) K ferro- or ferrimagnet CeNiIn 2 [6] has been reported. * Correspondence and reprints: Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 36, 48149 Münster, Germany. Tel.: +49 251 83 36001; fax: +49 251 83 36002. E-mail addresses: uflatka@cyf-kr.edu.pl (K. L ˛ atka), Roman.Kmiec@ifj.edu.pl (R. Kmie´ c), Andrzej.Pacyna@ifj.edu.pl (A.W. Pacyna), ncgurgul@cyf-kr.edu.pl (J. Gurgul), vazar@franko.lviv.ua (V.I. Zaremba), pottgen@uni-muenster.de (R. Pöttgen). From a structural point of view, GdNiIn 2 is the most in- teresting indide in this series. It crystallizes with a MgCuAl 2 type low-temperature (LT) modification [3] and transforms to a high-temperature (HT) modification [9] that is an intergrowth structure with MgCuAl 2 related slabs. The magnetic properties of the low-temperature modification are reported herein. 2. Experimental 2.1. Synthesis Starting materials for the preparation of LT-GdNiIn 2 were gadolinium ingots (Johnson–Matthey), nickel wire (∅ 0.38 mm, Johnson–Matthey), and indium tear drops (Heraeus), all with stated purities better than 99.9%. In a first step, pieces of the gadolinium ingot were arc-melted [10] to a small button under an argon atmosphere of ca. 600 mbar. The argon was previ- ously purified over molecular sieves, silica gel, and titanium sponge (900 K). The pre-melting of gadolinium strongly re- duces shattering during the subsequent reaction with nickel and indium. The gadolinium button was then mixed with pieces of 1293-2558/$ – see front matter  2006 Elsevier SAS. All rights reserved. doi:10.1016/j.solidstatesciences.2005.11.005