Structural, electronic, and magnetic investigation of magnetic ordering in MBE-grown CrxSb2-xTe3 thin films
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We report the structural, electronic, and magnetic study of Cr-doped Sb2Te3 thin films grown by a two-step deposition process using molecular-beam epitaxy (MBE). The samples were investigated using a variety of complementary techniques, namely, x-ray diffraction (XRD), atomic force microscopy, SQUID magnetometry, magneto-transport, and polarized neutron reflectometry (PNR). It is found that the samples retain good crystalline order up to a doping level of x = 0.42 (in CrxSb2-xTe3), above which degradation of the crystal structure is observed by XRD. Fits to the recorded XRD spectra indicate a general reduction in the c-axis lattice parameter as a function of doping, consistent with substitutional doping with an ion of smaller ionic radius. The samples show soft ferromagnetic behavior with the easy axis of magnetization being out-of-plane. The saturation magnetization is dependent on the doping level, and reaches from ~2 μBto almost 3 μB per Cr ion. The transition temperature (Tc) depends strongly on the Cr concentration and is found to increase with doping concentration. For the highest achievable doping level for phase-pure films of x = 0.42 ,a Tc of 125 K was determined. Electric transport measurements find surface-dominated transport below ∼10 K. The magnetic properties extracted from anomalous Hall effect data are in excellent agreement with the magnetometry data. PNR studies indicate a uniform magnetization profile throughout the film, with no indication of enhanced magnetic order towards the sample surface.
Collins-McIntyre , L J , Duffy , L B , Singh , A , Steinke , N -J , Kinane , C J , Charlton , T R , Pushp , A , Kellock , A J , Parkin , S S P , Holmes , S N , Barnes , C H W , van der Laan , G , Langridge , S & Hesjedal , T 2016 , ' Structural, electronic, and magnetic investigation of magnetic ordering in MBE-grown Cr x Sb 2-x Te 3 thin films ' , EPL , vol. 115 , no. 2 , 27006 . https://doi.org/10.1209/0295-5075/115/27006
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DescriptionThis work arises from research funded by the John Fell Oxford University Press Research Fund. LJC-M and LBD acknowledge financial support from EPSRC. LBD acknowledges financial support from the Science and Technology Facilities Council (UK) and AS from the Cambridge Commonwealth Trust.
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