Huge magnetoresistance and ultrasharp metamagnetic transition in polycrystalline Sm0.5Ca0.25Sr0.25MnO3

Abstract

Large magnetoresistive materials are of immense interest for a number of spintronic applications by developing high density magnetic memory devices, magnetic sensors and magnetic switches. Colossal magnetoresistance, for which resistivity changes several order of magnitude (∼ 10 4 %) in an external magnetic field, occurs mainly in phase separated oxide materials, namely manganites, due to the phase competition between the ferromagnetic metallic and the antiferromagnetic insulating regions. Can one further enhance the magnetoresistance by tuning the volume fraction of the two phases? In this work, we report a huge colossal magnetoresistance along with the ultra-sharp metamagnetic transition in half doped Sm0.5Ca0.25Sr0.25M nO3 manganite compound by suitably tuning the volume fraction of the competing phases. The obtained magnetoresistance value at 10 K is as large as ∼ 10 13 % in a 30 kOe external magnetic field and ∼ 10 15 % in 90 kOe external magnetic field and is several orders of magnitude higher than any other observed magnetoresistance value reported so far. Using model Hamiltonian calculations we have shown that the inhomogeneous disorder, deduced from tunneling electron microscopy, suppresses the CE-type phase and seeds the ferromagnetic metal in an external magnetic field. arXiv:1710.03007v2 [cond-mat.mtrl-sci]

Designing multi-level resistance states for multi-bit storage using half doped manganites

“…We use spin-fermion Monte Carlo (MC) technique based on the travelling cluster approximation [35,36] (TCA) for 24×24 lattice (see Ref. [30] for details). We ensured that the system is well annealed (using 10 4 Monte Carlo system sweeps in general) at each temperature.…”

“…We measure λ, J, ∆, h and T (temperature) in units of kinetic hopping parameter t. The estimated value of t in manganites is 0.2 eV [31]. We use J = 0.1, λ = 1.65 and ∆=0.3 for SCSMO [30]. Magnetization [= (S(q)) 0.5 at wave vector q = (0, 0), where S(q) is magnetic structure factor = 1 24 2 ij S i •S j e iq•(r i −r j ) ] is averaged over ten different disorder configurations in addition to the thermal averages obtained during the Monte Carlo simulations.…”

“…In the present communication, we report a multilevel resistive system by tuning the phase competition in a half doped manganites. The charge-ordered antiferromagnetic insulating (CO-AFM-I) state, in our Sm 0.5 Ca 0.25 Sr 0.25 M nO 3 (SCSMO) sample, melts to a ferromagnetic (FM) metallic state at a moderate magnetic field 70 kOe (one can use any field greater than critical field value ∼45 kOe [30]) at 10 K and the system converts to a phase coexisted metallic state after the removal of the magnetic field. During the zero field warming, we stop at four representative temperatures (35 K, 45 K, 52 K, 58 K) and perform temperature cycling between each representative temperatures and 10 K. Distinctly different magnetization and resistivity data generated at above four representative temperatures remains more or less unchanged during the temperature cycling.…”

“…The bifurcation between ZFCW and FCW curves in SCSMO as well as peak in ZFCW indicates that small but finite ferromagnetic fractions are induced in SCSMO which is absent in SCMO. This is due to the substitution of larger Sr ions in place of Ca in the parent compound Sm 0.5 Ca 0.5 M nO 3 [30]. The dip in the dM/dT vs. T curve for SCSMO [see the inset of Fig.…”

Possible Routes to Obtain Enhanced Magnetoresistance in a Driven Quantum Heterostructure with a Quasi-Periodic Spacer

“…In the present work, we are interested in the giant magnetoresistance (GMR) effect [41][42][43][44][45][45][46][47][48][49][50][51] , which was undoubtedly one of the groundbreaking works in the late 80s. The Nobel winning work [6,9,23,26,29] in the year 2007 by Albert Fert and Peter Grünberg has enriched the area of spintronics along with immense technological progress such as magnetic recording, storage and sensor industries, and many more [52][53][54][55].…”