Stoichiometry-driven metal-to-insulator transition in NdTiO 3/SrTiO3 heterostructures

Peng Xu; Daniel Phelan; Jong Seok Jeong; K. Andre Mkhoyan; Bharat Jalan

doi:10.1063/1.4866867

Stoichiometry-driven metal-to-insulator transition in NdTiO ₃/SrTiO₃ heterostructures

Peng Xu, Daniel Phelan, Jong Seok Jeong, K. Andre Mkhoyan, Bharat Jalan

Chemical Engineering and Materials Science

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Abstract

By controlling stoichiometry via a hybrid molecular beam epitaxy approach, we report on the study of thin film growth and the electronic transport properties of phase-pure, epitaxial NdTiO₃/SrTiO₃ heterostructures grown on (001) (La_0.3Sr_0.7)(Al _0.65Ta_0.35)O₃ (LSAT) substrates as a function of cation stoichiometry in NdTiO₃. Despite the symmetry mismatch between bulk NdTiO₃ and the substrate, NdTiO₃ films grew in an atomic layer-by-layer fashion over a range of cation stoichiometry; however amorphous films resulted in cases of extreme cation non-stoichiometry. Temperature-dependent sheet resistance measurements were consistent with Fermi-liquid metallic behavior over a wide temperature range, but revealed a remarkable crossover from metal-to-insulator (M-I) type behavior at low temperatures for all compositions. A direct correlation between cation stoichiometry, transport behavior, and the temperature of M-I transition is established.

Original language	English (US)
Article number	082109
Journal	Applied Physics Letters
Volume	104
Issue number	8
DOIs	https://doi.org/10.1063/1.4866867
State	Published - Feb 24 2014

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title = "Stoichiometry-driven metal-to-insulator transition in NdTiO 3/SrTiO3 heterostructures",

abstract = "By controlling stoichiometry via a hybrid molecular beam epitaxy approach, we report on the study of thin film growth and the electronic transport properties of phase-pure, epitaxial NdTiO3/SrTiO3 heterostructures grown on (001) (La0.3Sr0.7)(Al 0.65Ta0.35)O3 (LSAT) substrates as a function of cation stoichiometry in NdTiO3. Despite the symmetry mismatch between bulk NdTiO3 and the substrate, NdTiO3 films grew in an atomic layer-by-layer fashion over a range of cation stoichiometry; however amorphous films resulted in cases of extreme cation non-stoichiometry. Temperature-dependent sheet resistance measurements were consistent with Fermi-liquid metallic behavior over a wide temperature range, but revealed a remarkable crossover from metal-to-insulator (M-I) type behavior at low temperatures for all compositions. A direct correlation between cation stoichiometry, transport behavior, and the temperature of M-I transition is established.",

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AU - Andre Mkhoyan, K.

AU - Jalan, Bharat

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AB - By controlling stoichiometry via a hybrid molecular beam epitaxy approach, we report on the study of thin film growth and the electronic transport properties of phase-pure, epitaxial NdTiO3/SrTiO3 heterostructures grown on (001) (La0.3Sr0.7)(Al 0.65Ta0.35)O3 (LSAT) substrates as a function of cation stoichiometry in NdTiO3. Despite the symmetry mismatch between bulk NdTiO3 and the substrate, NdTiO3 films grew in an atomic layer-by-layer fashion over a range of cation stoichiometry; however amorphous films resulted in cases of extreme cation non-stoichiometry. Temperature-dependent sheet resistance measurements were consistent with Fermi-liquid metallic behavior over a wide temperature range, but revealed a remarkable crossover from metal-to-insulator (M-I) type behavior at low temperatures for all compositions. A direct correlation between cation stoichiometry, transport behavior, and the temperature of M-I transition is established.

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Stoichiometry-driven metal-to-insulator transition in NdTiO ₃/SrTiO₃ heterostructures

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