Elastic strain control of electronic structure, and magnetic properties of [Pr1−xCaxMnO3/SrTiO3]15 superlattices

Abstract

We report the growth, electronic structure, and in-plane magnetic properties of pulsed laser deposition grown 2D superlattice structures [Pr0.7Ca0.3MnO3/SrTiO3]15 and [Pr0.5Ca0.5MnO3/SrTiO3]15 on (001) oriented SrTiO3 and LaAlO3 single crystal substrates. The x-ray reflectivity measurements reveal well-defined interfaces between the manganite and titanate layers along with the existence of Kiessig fringes, providing the evidence for the smooth periodic superlattice structure. The reciprocal space mapping provides signature of tetragonal distortion in all the superlattices. The electronic structure determined from the x-ray photoelectron spectroscopy reveals divalent Sr and Ca, tetravalent Ti, and mixed valent Mn with a pronounce shift of binding energy peaks toward the higher energy side in the superlattices grown on (001) oriented LaAlO3 as compared to those grown on SrTiO3. These superlattices exhibit highly anisotropic ferromagnetic character. We used the law of approach to saturation to determine the anisotropy field (HK) and cubic anisotropy constant (K1) for all the investigated superlattices. This analysis yields the highest HK∼9 kOe and K1∼8×105 erg/cc for the [Pr0.7Ca0.3MnO3/SrTiO3]15 superlattice system. Furthermore, significant enhancement of the overall magnetic moment and a decrease in TC (<100 K) was observed in the case of LaAlO3 grown superlattice, which indicates a substantial role of residual elastic strain on the magnetic ordering. Our results indicate that the strain induced elongation of MnO6 octahedra leads to finite possibility of non-orthogonal overlapping of orbitals in the presence of large crystal field splitting of eg levels, which, in turn, causes suppression of the ferromagnetic double exchange interaction.

Influence of heat sintering on the physical properties of bulk La0.67Ca0.33MnO3 perovskite manganite: role of oxygen in tuning the magnetocaloric response

“…Thus, the intensity of Mn–O in LCM12 is comparatively lower than that in other specimens, indicating that the sample contains an abundance of oxygen and is dominated by the surface effects. 54 The higher binding energy peak (marked as O # ) between 532.62–533.42 eV might be the result of surface species like carbonyl groups or crystal lattice defects. It is argued that elements located at the outermost surface have larger binding energies than their bulk-bound counterparts, which means that surface sites often display less stability than bulk sites due to the abrupt termination of the bulk lattice structure.…”

Anisotropic Ferromagnetic Organic Nanoflowers

“…A similar trend has been noticed in case of M max ( T ) as well, except for reaching a peak at low temperatures, which shows a maximum value of 116 emu/mol at 2 K. Interestingly, the temperature variation of the differential magnetic moment, d M max /d T (shown on the right-hand-side panel), is consistent with the peak-zone of the H C ( T ). To understand the role of the magnetocrystalline anisotropy on the domain orientation of the investigated system, we employed the law of approach to saturation (LAS) technique assuming the system is having the highest symmetry. − Accordingly, the virgin magnetization isotherm obtained from the SQUID magnetometer is fitted with the mathematical expression corresponding to LAS eq (as given below).…”

Reentrant canonical spin-glass dynamics and tunable field-induced transitions in (GeMn)Co2O4 Kagomé lattice

“…The transitions correspond to the 2p 3/2 and 2p 1/2 signifies the presence of Mn 4+ state with the energy difference between the doublets M 1 and M 2 being ∆E Mn = 11.82 eV, which is close to the reported value of ∼11.8 eV corresponding to the tri-/or tetravalent state of Mn. If Mn exists in trivalent state, the binding energy difference should be close to 11.25 eV, while for the case of divalent state, the magnitude of ∆E Mn should be around 10.66 eV [36]. Since the binding energy separation for Mn 3+ and Mn 4+ state lies within the same range (11.25-11.8 eV) we assume that tetravalent electronic state of Mn is prominent in the investigated system [37].…”

“…The relevant fitting parameters obtained from the XPS spectrum are listed in (supplementary table) table 1S for all the elements present in the current system. Next, we focus on the core level XPS spectrum of Mn-2p as shown in figure 3(c) which consists of two highly intense peaks M 1 and M 2 located at 641.56 eV and 653.38 eV, respectively, along with one broad satellite transition S 1 at 644.48 eV [35,36]. The transitions correspond to the 2p 3/2 and 2p 1/2 signifies the presence of Mn 4+ state with the energy difference between the doublets M 1 and M 2 being ∆E Mn = 11.82 eV, which is close to the reported value of ∼11.8 eV corresponding to the tri-/or tetravalent state of Mn.…”