Journal of Alloys and Compounds 461 (2008) 21–25 Magnetic and electrical transport properties of Cr 3 (Se 1-x Te x ) 4 compounds Y.B. Li a,b,∗ , E. Br ¨ uck b , O. Tegus b , Y.Q. Zhang a , W.J. Feng a , N.K. Sun a , D. Li a , J. Li a , T.J. Gortenmulder b , Y.K. Huang b , Z.D. Zhang a a Shenyang National Laboratory for Materials Science, Institute of Metal Research, and International Centre for Materials Physics, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, People’s Republic of China b Van der Waals-Zeeman Instituut, Universiteit van Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam, The Netherlands Received 16 April 2006; received in revised form 3 July 2007; accepted 4 July 2007 Available online 10 July 2007 Abstract The magnetic and electrical transport behaviors of Cr 3 (Se 1-x Te x ) 4 compounds are investigated. A transition from antiferromagnetism to ferro- magnetism occurs at x = 0.2 in this system and abnormal changes of the lattice parameter a and angle β take place around the magnetic transition point. When Se is partially substituted by Te, a minimum of resistivity (ρ min ) is observed in the temperature dependence of resistivity. The temper- ature T min , where the minimum ρ min is, increases with Te concentration. The minimum in resistivity at T min is ascribed to the competition between a diminishing resistivity due to domain ordering and a rising resistivity due to disordered frozen spins in each domain. The electrical transport behavior below T min is described by hopping conductivity in terms of variable range—hopping. An external magnetic field affects strongly the resis- tivity of the Cr 3 (Se 1-x Te x ) 4 compounds, which shifts the magnetic ordering temperature T MO to higher temperature and T min to lower temperature. Subsequently, a negative magnetoresistance is found in this system. © 2007 Elsevier B.V. All rights reserved. Keywords: Magnetic; Resistivity; Metal–insulator transition; Magnetoresistance Transport properties of magnetic materials have been the subject of rather intensive research for decades. Several types of materials have been categorized as “giant” or “colossal” magnetoresistance (GMR or CMR) materials [1–8]. It is well established that the electronic transport properties of materials are very sensitive to the electronic structure as well as to the type of magnetism. Compounds of 3d transition metals with group VIB elements (S, Se, Te) exhibit a variety of structural, optical, and thermal properties [9]. Additionally, these compounds have a good combination of both abnormal electrical and magnetic properties. It is known that Cr 3 Se 4 is antiferromagnetic with a N´ eel temperature T N of about 80 K, and forms in a monoclinic structure with an ordered arrangement of vacant chromium sites [10,11]. On the other hand, the isostructural compound Cr 3 Te 4 ∗ Corresponding author at: Shenyang National Laboratory for Materials Sci- ence, Institute of Metal Research, and International Centre for Materials Physics, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, People’s Republic of China. E-mail address: ybli@imr.ac.cn (Y.B. Li). is ferromagnetic with a Curie temperature T C of about 320 K [12–14]. Similar to the pseudobinary Mn 1-x Cr x Te system [15], Cr 3 Se 4 and Cr 3 Te 4 have the same crystal structure and a compar- atively small difference in their lattice constants. We attempt in this work to combine Cr 3 Se 4 and Cr 3 Te 4 together, to form a com- plete solid solution in the Cr 3 (Se 1-x Te x ) 4 system. It is expected that a transition from antiferromagnetism to ferromagnetism may occur at a certain value of the composition. Furthermore, Cr 3 Se 4 appears to be a semiconductor [16], whereas Cr 3 Te 4 is a metal [17]. It is interesting to study whether there exist some abnormal magnetic or electrical transport properties, arising from the incomplete d-shells of the transition-metals component at a certain composition region. Hence, in the present work, we investigate in details the magnetic and electrical transport prop- erties of Cr 3 (Se 1-x Te x ) 4 compounds with nominal composition x = 0, 0.1, 0.2, 0.3 and 0.4. The specimens were prepared by the solid reaction of Cr (99.95%), Se (99.999%) and Te (99.999%) powders. The start- ing materials were mixed in the desired proportion and pressed into pellets. An excess (4at.%) of Se and Te over the stoi- 0925-8388/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2007.07.003