Metal-insulator transitions in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">NdNiO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>thin films

Catalán, Gustau; Bowman, R. M.; Gregg, J. M.

doi:10.1103/physrevb.62.7892

Cited by 159 publications

(143 citation statements)

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“…Rare earth nickelates are found to exhibit variable range hopping at low temperatures 26,33 where it is energetically favorable for an electron to hop to a site that is closer in energy than the nearest neighbor leading to VRH and is given by…”

Section: Resultsmentioning

confidence: 99%

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Sign reversal of magnetoresistance in a perovskite nickelate by electron doping

et al. 2016

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We present low temperature resistivity and magnetotransport measurements conducted on pristine and electron doped SmNiO3 (SNO). The low temperature transport in both pristine and electrondoped SNO shows a Mott variable range hopping with a substantial decrease in localization length of carriers by one order in the case of doped samples. Un-doped SNO films show a negative magnetoresistance (MR) at all temperatures characterized by spin fluctuations with the evolution of a positive cusp at low temperatures. In striking contrast, upon electron doping of the films via hydrogenation, we observe a crossover to a linear non-saturating positive MR∼ 0.2 % at 50 K . The results signify the role of localization phenomena in tuning the magnetotransport response in doped nickelates. Ionic doping is therefore a promising approach to tune magnetotransport in correlated perovskites.

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Section: Resultsmentioning

confidence: 99%

“…In case of NdNiO 3 , the low temperature resistivity behavior was modeled as a combination of activation and variable range hopping (VRH) 26 . SNO thin films have also been shown to exhibit variable range hopping at low temperatures 27 .…”

Section: Introductionmentioning

confidence: 99%

Sign reversal of magnetoresistance in a perovskite nickelate by electron doping

et al. 2016

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“…(Pbnm) to a monoclinic (P21/n) crystal structure. Further, the transition temperature depends on epitaxial strain [26], demonstrating sensitivity to lattice distortions.…”

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confidence: 99%

Spatially resolved ultrafast magnetic dynamics initiated at a complex oxide heterointerface

et al. 2015

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Diffraction is used to determine the spatial and temporal evolution of the magnetic disordering. We observe a magnetic melt front that grows from the substrate interface into the film, at a speed that suggests electronically driven propagation.Light control and ultrafast phase front propagation at hetero-interfaces may lead to new opportunities in optomagnetism, for example by driving domain wall motion to transport information across suitably designed devices. 3/25! ! !In transition metal oxides, rearrangements in electronic and magnetic properties can be triggered by the application of magnetic [5] and electric fields [6], or pressure [7,8].Switching has also been demonstrated in these materials using femtosecond optical excitation, at near-visible [9,10,11,12,13,14,15], mid-infrared [16,17,18,19,20] edge. The bandwidth of the X-ray pulses was reduced to below 1 eV by a grating monochromator. Diffracted X-rays were detected as function of the time delay relative to the mid-infrared excitation pulses. An avalanche photodiode enabled pulse-to-pulse normalization of the diffracted to the incident light intensity. where the latter is limited by the jitter between the FEL and the optical laser. We compare these dynamics to the time needed for the film to become metallic, as measured by the transient reflectivity in the 1−5 THz range induced by the same mid-infrared excitation (green dots in Fig. 1(d)). These two similar timescales, which reflect only average changes over the whole film, suggest an intimate connection between the insulator-to-metal transition and the melting of magnetic order.In Figure 2, we plot the transient θ-2θ scans for the (1/4 1/4 1/4) diffraction peak, sensitive to the out-of-plane antiferromagnetic ordering. In equilibrium, i.e. at negative time delay, a narrow diffraction peak and Laue oscillations are observed, attesting to the presence of magnetic order across the entire 30-nm film height, with sharp magnetic boundaries.Figure 2 further shows that a significant peak broadening and a suppression of the Laue oscillations accompany the strong photo-induced reduction in peak intensity. The broadening of the diffraction peak implies that the excitation melts the magnetic order only over a fraction of the film along the sample growth direction. Secondly, the suppression of the Laue oscillations indicates that the boundary between the ordered and disordered regions of the film is not sharp.We also find that throughout these dynamics the in-plane correlation length, as measured by transverse rocking curves (θ scans), remains unchanged (see Supplementary 6/25! ! ! Information). Hence, the dynamics discussed here are one dimensional, evolving along the sample growth direction.!The spatial distribution of the magnetic order at a time delay τ was analyzed quantitatively with the following expression for kinematic diffractionHere, the magnetic profile is represented by the space-and time-dependent structure factor F(z,τ), where ! = 4! sin ! ! is the magnitude of the scattering wave vector (with θ th...

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“…The metal-insulator transition in nickelates has been investigated so far using static experimental techniques that directly affect the electronic bandwidth through the Ni-O-Ni bond angle, such as chemical [14,15] and hydrostatic pressure [16,17] or epitaxial strain [18]. Recently it was also shown that electrostatic fields can be used to control the metal-insulator transition in these materials [19].…”

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confidence: 99%

“…Additionally, charge disproportionation between adjacent Ni sites is associated with different Ni-O bond lengths [11,12]. At low temperatures, the nickelates also possess an unusual antiferromagnetic spin arrangement [13].The metal-insulator transition in nickelates has been investigated so far using static experimental techniques that directly affect the electronic bandwidth through the Ni-O-Ni bond angle, such as chemical [14,15] and hydrostatic pressure [16,17] or epitaxial strain [18]. Recently it was also shown that electrostatic fields can be used to control the metal-insulator transition in these materials [19].…”

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Ultrafast Phase Control in Oxide Thin Films

Calderón¹

2012

Physics

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We report on ultrafast optical experiments in which femtosecond midinfrared radiation is used to excite the lattice of complex oxide heterostructures. By tuning the excitation energy to a vibrational mode of the substrate, a long-lived five-order-of-magnitude increase of the electrical conductivity of NdNiO 3 epitaxial thin films is observed as a structural distortion propagates across the interface. Vibrational excitation, extended here to a wide class of heterostructures and interfaces, may be conducive to new strategies for electronic phase control at THz repetition rates. DOI: 10.1103/PhysRevLett.108.136801 PACS numbers: 73.90.+f, 78.47.Àp Complex oxide heterostructures have emerged as multifunctional materials of striking flexibility, in which unconventional electronic phases can be realized by engineering the strain field across interfaces [1][2][3][4][5]. This same mechanical coupling is also expected to be effective on the ultrafast timescale, and could be exploited for the dynamic control of materials properties. Here, we demonstrate that a largeamplitude midinfrared field, made resonant with a stretching mode of the substrate, can switch the electronic properties of a thin film across an interface. Exploiting dynamic strain propagation between different components of a heterostructure, insulating antiferromagnetic NdNiO 3 is driven through a prompt, five-order-of-magnitude increase of the electrical conductivity, with resonant frequency and susceptibility that is controlled by choice of the substrate material.Many of the functional properties of ABO 3 perovskite oxides are extremely sensitive to rotation and tilting of the BO 6 octahedra, which control the hopping amplitudes and the exchange interaction through the B-O-B bond angle and length. It follows that one can engineer the electronic and magnetic properties by designing or actively controlling such distortions [6][7][8], or by coupling them to other structural instabilities [9,10]. One class of materials in which octahedral rotations and distortions have been linked to changes in the electronic structure are the rare earth nickelates, which display a sharp transition from a high-temperature metallic to a low-temperature insulating state. In the bulk, this electronic phase transition is accompanied by a structural change from an orthorhombic (Pbnm) to a monoclinic (P2 1 =n) symmetry with an increase in the Ni-O-Ni bond bending and the appearance of a charge density wave. Additionally, charge disproportionation between adjacent Ni sites is associated with different Ni-O bond lengths [11,12]. At low temperatures, the nickelates also possess an unusual antiferromagnetic spin arrangement [13].The metal-insulator transition in nickelates has been investigated so far using static experimental techniques that directly affect the electronic bandwidth through the Ni-O-Ni bond angle, such as chemical [14,15] and hydrostatic pressure [16,17] or epitaxial strain [18]. Recently it was also shown that electrostatic fields can be used to control the metal-i...

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Metal-insulator transitions inNdNiO3thin films

Cited by 159 publications

References 31 publications

Sign reversal of magnetoresistance in a perovskite nickelate by electron doping

Sign reversal of magnetoresistance in a perovskite nickelate by electron doping

Spatially resolved ultrafast magnetic dynamics initiated at a complex oxide heterointerface

Ultrafast Phase Control in Oxide Thin Films

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