Negative magnetoresistance in epitaxial films of neodymium nickelate

Stupakov, O.; Pacherová, O.; Kocourek, T.; Jelínek, M.; Dejneka, A.; Tyunina, M.

doi:10.1103/physrevb.99.085111

Cited by 17 publications

(18 citation statements)

References 30 publications

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“…Epitaxial NNO films of ~ 20 nm in thickness were grown by pulsed laser deposition as described before 11 – 14 , 20 . To introduce oxygen vacancies, oxygen pressure of deposition, p O2 , was varied from 20 Pa for stoichiometric growth to as low as 0.1 Pa (see Methods section).…”

Section: Resultsmentioning

confidence: 99%

Anisotropic chemical expansion due to oxygen vacancies in perovskite films

Tyunina

Pacherová

Kocourek

et al. 2021

Sci Rep

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In scientifically intriguing and technologically important multifunctional ABO3 perovskite oxides, oxygen vacancies are most common defects. They cause lattice expansion and can alter the key functional properties. Here, it is demonstrated that contrary to weak isotropic expansion in bulk samples, oxygen vacancies produce strong anisotropic strain in epitaxial thin films. This anisotropic chemical strain is explained by preferential orientation of elastic dipoles of the vacancies. Elastic interaction of the dipoles with substrate-imposed misfit strain is suggested to define the dipolar orientation. Such elastic behavior of oxygen vacancies is anticipated to be general for perovskite films and have critical impacts on the film synthesis and response functions.

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Section: Resultsmentioning

confidence: 99%

Anisotropic chemical expansion due to oxygen vacancies in perovskite films

Tyunina

Pacherová

Kocourek

et al. 2021

Sci Rep

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“…Only another NNO film on LSAT of 20 nm thickness demonstrates a similar MIT behavior as the reference epitaxial film considered in the main text (compare Figures 2a and A2a). The rest of the tested films do not display MIT above −190 °C, which is common for these materials and substrates [6][7][8][9]. Blue light illumination with the reference optical power 0.8 W (~0.4 J•mm −2 energy density) results in a comparable increase in the film resistivity by 5-8% (compare Figures 3a, A2b and A3b).…”

Section: Discussionmentioning

confidence: 74%

“…Figure 2 presents the resistivity as a function of temperature for both films. As illustrated by Figure 2a, the epitaxial NNO film demonstrates a typical behavior with a pronounced MIT at T MI ≈ −105 • C (170 K), a narrow low-temperature hysteresis ~5 • C and relevant resistivity values ρ ≈ 0.6 mΩ•cm at room temperature [3][4][5][6][7][8][9]. Contrary to that, the amorphous film shows a strong insulating behavior with a fivefold exponential drop of resistivity with a temperature increase from 26 to 70 • C (see Figure 2b).…”

Section: Resultsmentioning

confidence: 98%

“…A film-substrate mismatch in the lattice parameters introduces a strain influencing the resistive behavior of the nickelate thin films as compared with their bulk analogues [4,5]. For instance, the most studied NNO films subjected to a tensile strain of ~2% have T MI ≈ 170 K, whereas a small compressive strain of <−0.3% fully suppresses MIT in these films [6][7][8][9]. Recently, T MI at room temperature range is observed in SNO/NNO repetitive heterostructures with a few unit-cell thicknesses of separate layers [10].…”

Section: Introductionmentioning

confidence: 99%

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Large Negative Photoresistivity in Amorphous NdNiO3 Film

et al. 2021

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A significant decrease in resistivity by 55% under blue lighting with ~0.4 J·mm−2 energy density is demonstrated in amorphous film of metal-insulator NdNiO3 at room temperature. This large negative photoresistivity contrasts with a small positive photoresistivity of 8% in epitaxial NdNiO3 film under the same illumination conditions. The magnitude of the photoresistivity rises with the increasing power density or decreasing wavelength of light. By combining the analysis of the observed photoresistive effect with optical absorption and the resistivity of the films as a function of temperature, it is shown that photo-stimulated heating determines the photoresistivity in both types of films. Because amorphous films can be easily grown on a wide range of substrates, the demonstrated large photo(thermo)resistivity in such films is attractive for potential applications, e.g., thermal photodetectors and thermistors.

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“…[41] Here, variable-range hopping should be responsible for the carrier transport in the disordered interfacial structure of a-C/Q2DEG heterostructures. [42] The application of a magnetic field may give rise to Zeeman splitting of the Anderson localized states, [43][44][45] generating the spin dependent Zeeman shift ΔE Z = ±1/2gµ B H, where g is the Landé g-factor and µ B is the Bohr magneton. As a result, the Fermi level will split into the spin-up and spin-down subbands, which causes the inevitable redistribution of hopping carriers.…”

Section: Resultsmentioning

confidence: 99%

Rewritable Optical Memory Based on Sign Switching of Magnetoresistance

Liu

Lü

et al. 2019

Adv Elect Materials

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structure and lattice defects, whereas magnetic phenomena derive from spintronic characteristics and dynamics of charge carriers. [1,4-6] To be sure, coupling between optical and magnetic effects is well known through the Kerr and Faraday effects. [7,8] Recent advances of light-induced magnetization and light-controlled spin current have drawn extensive interest for promising applications of optical memory devices. [9,10] Light-controlled magnetism has been observed principally in magnetic materials. [11-14] It is also of interest for non-magnetic materials, for which incident photons tend to control the spin polarization, possibly causing a modulation in magnetoresistance (MR). [15,16] A worthwhile goal is to utilize photon energy to gain control of magnetic states, thus utilizing the storage feature of magnetic phenomena to achieve memory of optical signals. This strategy is expected to lead to optospintronic devices, [17] by combining the advantages of optical and magnetic characteristics. Compared with the traditional ferromagnetic memory devices, the direct storage of optical signals in optical memory devices is promising for applications in existing network systems, [18] especially when considering that the information transmission is almost always performed through optical fibers. Without extra signal conversions, the optical memory devices may decrease the loss of optical signals and enhance the efficiency of information transmission. Although much research has been reported on the optical control of spin current in non-magnetic materials, [15-17,19] few studies investigated the light-induced sign switching between positive magnetoresistance (PMR) and negative magnetoresistance (NMR). PMR occurs when electrical resistance increases as an applied external magnetic field increases; NMR is an opposite phenomenon-a decreasing resistance as magnetic field increases. NMR is usually caused by spindependent scattering or a magnetic-field-induced phase transition. [2,3] Generally, most materials show PMR effect due to Lorentz force. [20] In non-magnetic materials, the NMR effect is very rare and often depends on specific physical mechanisms, including strain effect, electrical gating, chiral anomaly in Weyl semimetals, and so on. [21-23] Exploring the light-induced NMR effect in non-magnetic systems may advance a physical understanding of optospintronics and provide a new route toward optical memory devices based on MR switching.

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Negative magnetoresistance in epitaxial films of neodymium nickelate

Cited by 17 publications

References 30 publications

Anisotropic chemical expansion due to oxygen vacancies in perovskite films

Anisotropic chemical expansion due to oxygen vacancies in perovskite films

Large Negative Photoresistivity in Amorphous NdNiO3 Film

Rewritable Optical Memory Based on Sign Switching of Magnetoresistance

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