Tuning the Phase Separation, Charge Ordering, and Electronic Transport in Electron‐Doped Manganite Films by Piezo‐Strain and Magnetic Field

Abstract

electron-doped) manganites have sparked a surge of research activities as a supplement for the divalent ions substituted (hole-doped) manganites, showing great potential for the development of all-manganites-based p-n junctions and electronic devices. [7][8][9][10] Unlike other tetravalent elements, hafnium has a sole tetravalent or zero valence state. This feature makes La 1-x Hf x MnO 3 an excellent candidate for investigating the electronic structures, Jahn-Teller lattice distortion and double-exchange interaction between the Mn 3+ -Mn 2+ ions in electron-doped manganites instead of that between the Mn 3+ -Mn 4+ ions in hole-doped manganites. The subtle balance of free energy between the coexistent phases in La 1-x Hf x MnO 3 films is always unstable and can thus be easily tipped by an external stimulus, such as current, magnetic field, stress, etc., which causes drastic modification of properties of the films. For example, Wang et al. [11] reported that a magnetic field of H = 6 T increases the Curie temperature by 32 K with a magnetoresistance (MR) of 300% near Curie temperature for La 0.9 Hf 0.1 MnO 3 films on SrTiO 3 substrates. Xing et al. [12] found current induced abnormal and giant electroresistance effect (1257%) and the change of the ground state from metallic to insulating phases for La 0.9 Hf 0.1 MnO 3 films on LaAlO 3 substrates. It is noteworthy that Wu et al. [13] observed that the substrate-induced epitaxial lateral tensile strain enhances the metal-to-insulator transition temperature as the thickness is reduced from 80 to 15 nm for La 0.8 Hf 0.2 MnO 3 films on SrTiO 3 substrates. This result is in contrast to those of other hole-doped manganite films, which isThe macroscopic physical properties and functionalities of strongly correlated complex oxides usually originate from and depend sensitively on microscopic interactions, which can be controlled by an external stimulus. Here, in electron-doped La 0.85 Hf 0.15 MnO 3 /Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 multiferroic heterostructure, the role of phase separation in manipulating charge ordering and electronic transport by piezo-strain and magnetic field is determined. The electric-field-induced lateral compressive piezo-strain suppresses the chargeordering transition temperature and decreases the film resistance with a giant gauge factor of 27 368, due to the enhancement of the double-exchange interaction between the Mn 3+ -Mn 2+ ions and the suppression of the electronphonon coupling stemming from the Jahn-Teller deformation. Moreover, the magnetic field can weaken the piezo-resistance effect by 342 times. This result, together with elastically controlled magnetoresistance effect, demonstrates intimate correlation between the piezo-strain-induced and magneticfield-induced effects by adjusting phase separation tendency. The findings indicate the importance of phase separation in multi-field quantum control of electron-doped perovskite manganites.

Recent Progress in Strain Engineering on Van der Waals 2D Materials: Tunable Electrical, Electrochemical, Magnetic, and Optical Properties

“…[99,100] Piezoelectric substrates such as Pb(Mg 1/3 Nb 2/3 ) and O 3 -PbTiO 3 (PMN-PT) have also been used to introduce strain in heterostructures involving the manganites. [101,102] Also, the ferroelectric ceramic material BaTiO 3 superlattices have been shown to induce strain when integrated into silicon and affect the magnetism of LaMnO 3 with the change of BaTiO 3 thickness. [98] In principle, such piezoelectric substrates should offer a promising method for electrically straining and tuning magnetic properties of 2D magnets, offering a platform to elucidate and explore the rich interplay between electric, magnetic, and lattice degrees of freedom in such artificial "multiferroic" heterostructures.…”

“…[104][105][106][107][108] In contrast, the ferromagnetic metal SrRuO 3 (SRO) has promising physical properties, including vertical hysteretic shift, magnetocrystalline anisotropy, exchange bias, and anomalous Hall effect for potential utilization in magnetic tunnel junctions and spin valves. [87,102] SRO films' lattice degree of freedom has been considered to offer a significant way to change their physical properties through external fields. For instance, lattice strain-mediated electric-field regulation of magnetic and electrical properties was achieved when an in-plane compressive strain was imposed on SRO films epitaxially grown on PMN-PT single crystals through the piezoelectric response.…”

Orientation-tunable ferroelectric and energy storage properties in PMN–PT single crystals

“…(1 − x)Pb(Mg 1/3 Nb 2/3 )O 3 -xPbTiO 3 (PMN-PT) materials have aroused wide concerns owing to their excellent ferroelectric properties and high piezoelectric coefficients. [20][21][22] The PT composition, electric field and temperature significantly affect the phase transition and electric properties. [23][24][25] However, limited systematic studies about crystal orientation-dependent ferroelectric and energy storage properties limit our deep understanding of the microscopic mechanism for the application of PMN-PT materials.…”

Polycrystalline La0.66Gd0.04Ca0.3MnO3 for magnetic-response applications: concurrent anisotropic magnetoresistance and magneto-transport under a low magnetic field

“…In this regard, several strategies for increasing the resistivity versus temperature ( ρ – T ) relationship, particularly among the M–I competing transitions, have been proposed in the literature to enhance the magnetic and electrical characteristics of manganites. These approaches include the controllable incorporation of dopant elements as occupancy ions, 10 the application of external electric stimuli 11 or the magnetic field modulations, 12 and the employment of modified synthesis procedures. 13 Consequently, doping-induced lattice distortion in manganites provides multiple avenues for tuning the double-exchange (DE) interaction 14 and enhancing the magneto-electronic functions, like MR and TCM.…”