Enhanced low-field magnetoresistance in La2/3Ca1/3MnO3/Pr2/3Ca1/3MnO3 superlattices

Li, H.; Sun, J. R.; Wong, H. K.

doi:10.1063/1.1445802

Cited by 45 publications

(38 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An MIT occurs beyond a threshold width similar as in the experiments by Li et al 30 who measured the variations in the resistivity in LCMO/PCMO superlattices for different widths of the PCMO layer. In addition, the inset in Fig.8(b) shows a hump in the resistivity for w = 9 and w = 7 at the ferromagnetic onset temperatures T≃ 0.04 and 0.05, respectively, while there is no such hump in the bulk FM manganite (see the dashed line of Fig.8(b)).…”

Section: Metal-insulator Transitionmentioning

confidence: 53%

“…With increasing AFI layer width, the induced ferromagnetic moment in the AFI layers decreases monotonically and drives an MIT in the superlattices. In addition to the large magnetoresistance our calculations explain the observed temperature crossover between positive and negative magnetoresistance and the two ferromagnetic transitions observed in the superlattices 30,36 .…”

Section: Introductionmentioning

confidence: 61%

“…The magnetic-profile for each layer follows the bulk phase diagram at the corresponding local density along with a weak proximity effect 23,27 . In the initial studies of manganite superlattices [28][29][30][31] the primary intent was to improve the tunneling magnetoresistance 32,33 in a FM/AFI superlattice where the constituent parent FM and AFI manganites have the same electron density, n = 1 − x. FM/AFI superlattices with different combinations of manganites (FM = LSMO, LCMO; AFI = PCMO, GdCMO; n = 0.67) 30,[34][35][36] have been studied in recent years. The observed induced ferromagnetic moment in the AFI layers depends on their width and the induced moment is tunable by an external magnetic field 30,36,37 .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Electronic and magnetic reconstructions in manganite superlattices

Pradhan

Kampf

2013

Phys. Rev. B

View full text Add to dashboard Cite

We investigate the electronic reconstruction at the interface between ferromagnetic metallic (FM) and antiferromagnetic insulating (AFI) manganites in superlattices using a two-orbital doubleexchange model including superexchange interactions, Jahn-Teller lattice distortions, and long range Coulomb interactions. The magnetic and the transport properties critically depend on the thickness of the AFI layers. We focus on superlattices where the constituent parent manganites have the same electron density n = 0.6. The induced ferromagnetic moment in the AFI layers decreases monotonically with increasing layer width, and the electron-density profile and the magnetic structure in the center of the AFI layer gradually return to the bulk limit. The width of the AFI layers and the charge-transfer profile at the interfaces control the magnitude of the magnetoresistance and the metal-insulator transition of the FM/AFI superlattices.

show abstract

Section: Metal-insulator Transitionmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electronic and magnetic reconstructions in manganite superlattices

Pradhan

Kampf

2013

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…To minimize disorder and strain effects isostructural interfaces are favorable. In a different approach NMI barriers were replaced by AFI manganites [13][14][15][16] . In the presence of a small external magnetic field not only the FM manganites align but there is a likely possibility that the magnetization in the AFI layer also aligns along the FM leads 13,15 .…”

mentioning

confidence: 99%

“…In a different approach NMI barriers were replaced by AFI manganites [13][14][15][16] . In the presence of a small external magnetic field not only the FM manganites align but there is a likely possibility that the magnetization in the AFI layer also aligns along the FM leads 13,15 . Specifically the relation between the magnetoresistance and the induced magnetic moment in the AFI barrier was established in LSMO/Pr 0.67 Ca 0.33 MnO 3 (PCMO)/LSMO superlattices 17 .…”

mentioning

confidence: 99%

Interfacial magnetism in manganite superlattices

Pradhan

Kampf

2013

Phys. Rev. B

View full text Add to dashboard Cite

We use a two-orbital double-exchange model including Jahn-Teller lattice distortions, superexchange interactions, and long-range Coulomb (LRC) interactions to investigate the origin of magnetically disordered interfaces between ferromagnetic metallic (FM) and antiferromagnetic insulating (AFI) manganites in FM/AFI superlattices. The induced magnetic moment in the AFI layer varies non-monotonically with increasing AFI layer width as seen in the experiment. We provide a framework for understanding this non-monotonic behavior which has a one-to-one correspondence with the magnetization of the FM interface. The obtained insights provide a basis for improving the tunneling magnetoresistance in FM/AFI manganite superlattices by avoiding a magnetic dead layer (MDL) in the FM manganite.The FM manganites have emerged as potential candidates for spintronics devices 1,2 due to their high spin polarization 3,4 .For the future generation of magnetic tunnel junctions (MTJs) artificial trilayers of insulating metal oxides sandwiched between FM manganites are currently designed. In MTJs a large tunneling magnetoresistance (TMR) 5 is observed by switching the spin orientation in the FM leads from antiparallel to parallel configurations; the TMR is defined by the ratio (R AP − R P )/R P where R AP and R P are the resistances for antiparallel and parallel orientations, respectively 6 . Although SrTiO 3 is predominantly used as the insulator between La 0.67 Sr 0.33 MnO 3 (LSMO) layers, also other combinations of FM and NMI oxides (FM = LSMO, La 0.67 Ca 0.33 MnO 3 (LCMO); NMI = TiO 2 , LaAlO 3 , NdGaO 3 ) have also been tested for their performance 7-10 .TMR is a spin dependent process which critically depends on the magnetic and the electronic properties of the interface between FM manganites and the insulating material 1 . In such a spin sensitive device it is required to have a structurally and magnetically well defined interface. It is an experimental fact that the magnetization of FM manganites decreases at the interface below its bulk value 11 , the origin of which is not well understood. The reduction of the magnetization at the interface, usually referred to as the 'magnetic dead layer' (MDL) 8,9 has an adverse effect on the TMR by decreasing the tunneling current, which by itself should be large for device applications. A recent microscopic analysis 12 suggests that the decrease of the double-exchange energy at an FM/SrTiO 3 interface is the origin of the MDL. The possible coexistence of different magnetic phases at the interface is however not accessible from such an analysis.The reduction of the magnetization has been attributed to phase separation, and/or electronic and magnetic reconstructions due to structural inhomogeneities at the interface. Unlike at the surface of FM manganites 3 it is a difficult task to determine the electronic and structural changes at interfaces which are several nanometers below the surface. To minimize disorder and strain effects isostructural interfaces are favorable. In a different approach...

show abstract

Large, Temperature‐Tunable Low‐Field Magnetoresistance in La_0.7Sr_0.3MnO₃:NiO Nanocomposite Films Modulated by Microstructures

Ning

Wang

Zhang

2014

Adv Funct Materials

View full text Add to dashboard Cite

5393www.MaterialsViews.com wileyonlinelibrary.com environment. [ 9,10 ] Recently, due to the deepening cognition of the intrinsic and extrinsic GMR effect, growing attention has been paid to polycrystalline manganites to obtain the extrinsic low-fi eld magnetoresistance (LFMR) by structuring grain boundaries, nanosized inclusions, interface phase, and artifi cial grain boundaries. What's more, the LFMR in composites or fi lms can be further improved by introducing a secondary phase (usually non-magnetic or antiferromagnetic insulators). [11][12][13][14][15][16][17][18][19][20] For example, the LFMR values of -6% at 5 K and 0.16 T in LSMO:SrTiO 3 superlattice structure, [ 3 ] -17.5% at 30 K and 1 T in LSMO:ZnO columnar structure, [ 21 ] -8% at 10-150 K and 1 T in LSMO:MgO nanorod arrays structure [ 22 ] and -12% at 77 K and 0.4 T in LSMO:Ag 0-3 structure [ 23 ] have been reported. However, neither the early results obtained from LSMO polycrystalline fi lms [ 24 ] or recent results obtained from LSMO:ZnO composite fi lms with a columnar structure, [ 21 ] enhanced LFMR values are always display in a low temperature range. That may be due to the large grain size in polycrystalline fi lms (≈µm) or weak spin coupling at the phase boundaries in the composite thin fi lms. Systems featuring a large LFMR at temperatures close to or even higher than room temperature are also interesting owing to their potential applications in magnetic fi eld sensing and data storage. [ 25 ] Dey et al. have found that the large LFMR will keep steady in a higher temperature range when the grain size is in nanoscale and gets pronounced with the decrease in particle size. [ 26 ] It is notable that the spin pinned effect occurs at the nanosized grain surface defect sites or spin coupling at the boundaries. [ 26,27 ] In addition, the short range ferromagnetic (FM) coupling order may add the opportunity of spin scattering even near the Curie temperature. [ 28,29 ] Thus it is speculated that the high-temperature LFMR in LSMO composite fi lms can be got through tuning the grain size and the FM coupling at the phase boundary. MacManus-Driscoll et al. proposed that the self-assembled composite fi lms are free from substrate clamping constraints and form strained vertical interface areas which can be used to tune the FM coupling by another phase and also can provide a more fl exible way to control the growth of the fi lms which can be used to control the grain size to get enhanced physical properties. [ 30 ] To prepare the LSMO-based composite fi lms, on the one hand, it should NiO nano composite thin fi lms, which will be expected to be applied in the devices using for a wide temperature range.

show abstract

Enhanced low-field magnetoresistance in La2/3Ca1/3MnO3/Pr2/3Ca1/3MnO3 superlattices

Cited by 45 publications

References 22 publications

Electronic and magnetic reconstructions in manganite superlattices

Electronic and magnetic reconstructions in manganite superlattices

Interfacial magnetism in manganite superlattices

Large, Temperature‐Tunable Low‐Field Magnetoresistance in La_0.7Sr_0.3MnO₃:NiO Nanocomposite Films Modulated by Microstructures

Contact Info

Product

Resources

About

Enhanced low-field magnetoresistance in La2/3Ca1/3MnO3/Pr2/3Ca1/3MnO3 superlattices

Cited by 45 publications

References 22 publications

Electronic and magnetic reconstructions in manganite superlattices

Electronic and magnetic reconstructions in manganite superlattices

Interfacial magnetism in manganite superlattices

Large, Temperature‐Tunable Low‐Field Magnetoresistance in La0.7Sr0.3MnO3:NiO Nanocomposite Films Modulated by Microstructures

Contact Info

Product

Resources

About

Large, Temperature‐Tunable Low‐Field Magnetoresistance in La_0.7Sr_0.3MnO₃:NiO Nanocomposite Films Modulated by Microstructures