Structural Manipulation of Phase Transitions by Self‐Induced Strain in Geometrically Confined Thin Films

Abstract

Strain engineering is a well-known method often used to tune material properties in thin films. The most studied sources of strain are lattice mismatch and differential thermal contraction between the substrate and film. However, in materials which undergo a structural phase transition (SPT), a third and often overlooked source of strain may play a very significant role. If the substrate confines the area of the film, the SPT may induce stress which changes the evolution of the transition. This is a 2D analog of the isochoric phase transition between water and ice, where the freezing point drops below 0 °C. To illustrate this, the prototypical Mott insulator V 2 O 3 which has an SPT coupled to a metal-insulator transition is used to show how self-induced strain can drastically alter structural and electronic properties. This effect provides an elegant approach for mapping the phase diagram of the SPT and the transitions coupled to it. Moreover, the magnitude of self-straining is tunable by modifying the substrate morphology. This effect may be important for numerous materials which exhibit an SPT and are subjected to geometrical constraints.

Non-universal current flow near the metal-insulator transition in an oxide interface

“…Coupling between electronic and lattice structures is characteristic of transition metal oxides 6,7 ; MITs often occur together with a magnetic or structural phase transition 8,11,[37][38][39][46][47][48] . To understand the electronic transitions, it is essential to determine how the structural/magnetic transitions contribute, and whether they are the driving force behind the MIT.…”

Strain Control of Phase Transition and Exchange Bias in Flexible Heusler Alloy Thin Films

“…The performances of MHAs strongly depend on the magnetic and structural phase transitions, which determine their practical operating temperatures. Therefore, the manipulation of phase transitions, which has been extensively studied, − is regarded as a challenge in modern material physics, particularly in Heusler-type Ni–Mn– X alloys. ,− The efficient control of phase transition in MHAs may provide an additional degree of freedom to expand the functions of present devices and help us to further understand the inherent mechanism of magnetostructural interactions.…”

“…The control of phase transition has been performed on various functional materials, involving metals and oxides, by varying external forces such as electric field, , strain, − and magnetic field. − Gong et al combined the Ni–Co–Mn–In ribbon with the PMN-PT substrate to investigate the effect of the electric field on the magnetocaloric effect. As the electric field increased from 0 to 8 kV·cm –1 , the strain induced by the converse piezoelectric effect of PMN-PT substrates increased the magnetostructural transformation temperature by about 7 K in the cooling process and 2 K in the heating process.…”

Metal–Insulator Transitions in Stable V2O3 Thin Films: Atomic Layer Deposition and Postdeposition Annealing Studies

“…In addition, the e σ g orbital is located parallel to the c-axis. [4] The MIT temperature for bulk V 2 O 3 is %155 K. The transition temperature and electrical resistivity for V 2 O 3 films can vary depending on the substrate, [5] deposition conditions, aand c-axes length ratios, [6][7][8] strain, [9,10] the lattice mismatch between substrate and film, [11] oxygen or vanadium vacancies, [12] and crystalline defects. [13,14] The MIT has been tuned by altering the stoichiometry of bulk V 2Àx O 3 and increasing the oxygen percentage, which lowers the transition temperature.…”