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Structural, electronic, and magnetic investigation of magnetic ordering in MBE-grown Cr x Sb 2−x Te 3 thin films

DOI: 10.1209/0295-5075/115/27006 DOI Help

Authors: L. J. Collins-mcintyre (University of Oxford) , L. B. Duffy (University of Oxford; ISIS) , A. Singh (University of Cambridge) , N-j Steinke (ISIS) , C. J. Kinane (ISIS) , T. R. Charlton (ISIS) , A. Pushp (IBM Almaden Research Center) , A. J. Kellock (IBM Almaden Research Center) , S. S. P. Parkin (IBM Almaden Research Center) , S. N. Holmes (Toshiba Research Europe Ltd) , C. H. W. Barnes (University of Cambridge) , G. Van Der Laan (Diamond Light Source) , S. Langridge (ISIS) , T. Hesjedal (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Epl (europhysics Letters) , VOL 115

State: Published (Approved)
Published: September 2016

Open Access Open Access

Abstract: 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 μB to 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 125K was determined. Electric transport measurements find surface-dominated transport below 10K. 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.

Journal Keywords: Topological insulator, PNR, MBE

Subject Areas: Physics, Materials

Diamond Offline Facilities: SQUID, and XRD
Technical Areas: Magnets , Theoretical Physics