We exploit the magnetic interlayer coupling in La0.7 Sr0. 3 MnO3/SrRuO3 superlattices to realize a crossover between inverse and conventional magnetic entropy changes. Our data reveal a strong anisotropic nature of the magnetocaloric effect due to the magnetic anisotropy of the superlattice. Therefore, artificial superlattices built from ferromagnetic materials that can be used to alter the magnetic structure as well as the magnetic anisotropy, could also be utilized for tuning the magnetocaloric properties, which may open a constructive approach for magnetic refrigeration applications. © 2010 American Institute of Physics.

Prahallad Padhan

Department Of Physics

ARTIFICIAL SUPERLATTICES

CONSTRUCTIVE APPROACH

Magnetic entropy change

MAGNETIC INTERLAYERS

Magnetic refrigeration

Magneto-caloric effects

Magnetocaloric properties

Ferromagnetic materials

Ferromagnetism

Magnetic devices

Manganese oxide

Superlattices

magnetic anisotropy

Fulltext

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IIT Madras

Applied Physics Letters

A series of superlattices consisting of 15 bilayers of ferromagnetic La0.7Sr0.3MnO3 (LSMO) and SrRuO3 (SRO) were grown with either stacking order on (1 1 1) oriented SrTiO3 (STO) substrates using the pulsed laser deposition technique. The Raman spectra of these superlattices show the existence of rhombohedral and orthorhombic crystal structures of LSMO in (111)STO/[11-unit cell (u.c.) LSMO/n-u.c. SRO]X15 superlattices with n = 2 and 3. Interestingly, the Raman spectra of (1 1 1)STO/[11-u.c. SRO/n-u.c. LSMO]X15 superlattices with n = 2 and 3 show only the orthorhombic structure of LSMO. The (1 1 1)STO/[11-u.c. LSMO/n-u.c. SRO]X15 superlattices exhibit enhanced magnetization with weak antiferromagnetic coupling whereas reduced magnetization with strong antiferromagnetic coupling is observed in (1 1 1)STO/[11-u.c. SRO/n-u.c. LSMO]X15 superlattices. The observed magnetic properties of these superlattices can be explained by the interfacial structural coupling, as evident from their Raman spectra which suggest a modification in the stereochemistry of Mn at the interfaces. © 2016 IOP Publishing Ltd.

Journal of Physics Condensed Matter

Effect of La0.7Sr0.3MnO3 crystal structures on magnetization of (1 1 1) oriented La0.7Sr0.3MnO3-SrRuO3 superlattices

We studied magnetic properties of bulk LaCrO3; a GdFeO3-type distorted perovskite, with a predominant antiferromagnetic phase transition at ∼290 K. The bulk LaCrO3 exhibits intrinsic weak ferro magnetism at room temperature, which may arise due to the tilting of CrO6 octahedra, resulting in a non-zero net magnetic moment, as confirmed from the magnetization measurements. A broad magnetically-induced entropy change (-ΔS) is observed with the maxima at 290 K, close to room temperature in LaCrO3 system. © 2015 IOP Publishing Ltd.

Materials Research Express

Magnetostructural and magnetocaloric properties of bulk LaCrO3 system

Superlattices consist of two ferromagnets La0.7Sr 0.3MnO3 (LSMO) and SrRuO3 (SRO) were grown in (110)-orientation on SrTiO3 (STO) substrates. The x-ray diffraction and Raman spectra of these superlattices show the presence of in-plane compressive strain and orthorhombic structure of less than 4 u.c. thick LSMO spacer, respectively. Magnetic measurements reveal several features including reduced magnetization, enhanced coercivity, antiferromagnetic coupling, and switching from antiferromagnetic to ferromagnetic coupling with magnetic field orientations. These magnetic properties are explained by the observed orthorhombic structure of spacer LSMO in Raman scattering which occurs due to the modification in the stereochemistry of Mn at the interfaces of SRO and LSMO. © 2014 AIP Publishing LLC.

Raman spectra and magnetization of all-ferromagnetic superlattices grown on (110) oriented SrTiO3

The switching of ferromagnetic-to-antiferromagnetic coupling of magnetization in the superlattices consisting of two ferromagnetic metals La 0.7Sr 0.3MnO 3 (LSMO) and SrRuO 3 (SRO) grown on (001) oriented SrTiO 3 has been observed by changing the orientation of the field from out-of-plane to in-plane direction. Such switching of magnetic coupling strongly depends on the stacking order of La 0.7Sr 0.3MnO 3 and SrRuO 3 layers in the superlattice of 20 unit cell (u.c.)/n (=3 or 5) u.c. thickness configuration. This is explained by the structural distortion in the MnO 6 and RuO 6 octahedra along the out-of-plane direction due to the observed stress. © 2011 American Institute of Physics.

Size effect on magnetic coupling in all-ferromagnetic superlattices

The Magnetocaloric Effect and its Applications

Physical Review Letters

Tailoring Magnetic Interlayer Coupling inLa0.7Sr0.3MnO3/SrRuO3Superlattices

Journal of Magnetism and Magnetic Materials

On the determination of the magnetic entropy change in materials with first-order transitions

Physical Review B

Magnetocaloric properties of Co/Cr superlattices

Critical thickness and orbital ordering in ultrathinLa0.7Sr0.3MnO3films

Anisotropic magnetocaloric effect in all-ferromagnetic (La0.7 Sr0.3 MnO3/SrRuO3) superlattices

Journal	Applied Physics Letters
ISSN	00036951
Open Access	No