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Large and Tunable Polar-Toroidal Coupling in Ferroelectric Composite Nanowires toward Superior Electromechanical Responses.

Chen WJ, Zheng Y, Wang B - Sci Rep (2015)

Bottom Line: Particularly, a strong polar-toroidal coupling that is tunable by the SrTiO3-layer thickness, temperature, external strains and electric fields is found to exist in the nanowires, with the appearance of fruitful dipole states (including those being purely polar, purely toroidal, both polar and toroidal, or distorted toroidal) and phase boundaries.As a consequence, an efficient cross control of the toroidal (polar) order by static (curled) electric field, and superior piezoelectric and piezotoroidal responses, can be achieved in the nanowires.The result provides new insights into the collective dipole behaviors in nanowire systems.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China [2] Micro &Nano Physics and Mechanics Research Laboratory, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China.

ABSTRACT
The collective dipole behaviors in (BaTiO3)m/(SrTiO3)n composite nanowires are investigated based on the first-principles-derived simulations. It demonstrates that such nanowire systems exhibit intriguing dipole orders, due to the combining effect of the anisotropic electrostatic interaction of the nanowire, the SrTiO3-layer-modified electrostatic interaction and the multiphase ground state of BaTiO3 layer. Particularly, a strong polar-toroidal coupling that is tunable by the SrTiO3-layer thickness, temperature, external strains and electric fields is found to exist in the nanowires, with the appearance of fruitful dipole states (including those being purely polar, purely toroidal, both polar and toroidal, or distorted toroidal) and phase boundaries. As a consequence, an efficient cross control of the toroidal (polar) order by static (curled) electric field, and superior piezoelectric and piezotoroidal responses, can be achieved in the nanowires. The result provides new insights into the collective dipole behaviors in nanowire systems.

No MeSH data available.


Schematics of the model system and the basic idea of this investigation.(a) A periodic (BaTiO3)m/(SrTiO3)n composite nanowire. (b) In the nanowire, the BaTiO3 region is under partial screening along one direction and open-circuit condition along the other directions. (i) A multi-order state with coexistence of polar and toroidal orders and (ii) cross coupling between toroidization g and static electric field EH, and between polarization P and curled electric field EC may be achieved.
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f1: Schematics of the model system and the basic idea of this investigation.(a) A periodic (BaTiO3)m/(SrTiO3)n composite nanowire. (b) In the nanowire, the BaTiO3 region is under partial screening along one direction and open-circuit condition along the other directions. (i) A multi-order state with coexistence of polar and toroidal orders and (ii) cross coupling between toroidization g and static electric field EH, and between polarization P and curled electric field EC may be achieved.

Mentions: Using first-principles-derived simulations, here we show that (BaTiO3)m/(SrTiO3)n nanowires (Fig. 1a) exhibit a large and tunable polar-toroidal coupling, which can lead to fruitful dipole states (including those being purely polar, purely toroidal, both polar and toroidal, or distorted toroidal) and phase boundaries, due to a combining effect of the anisotropic electrostatic interaction of the nanowire, the SrTiO3-layer-modified electrostatic interaction and the multiphase ground state of BaTiO3 layer (Fig. 1b). In the formula (BaTiO3)m/(SrTiO3)n, m and n refer to the thickness, in unit cells, of the (001) BaTiO3 and (001) SrTiO3 layers, respectively. In the nanowires, the polar and toroidal orders are intimately coupled as they are both carried by the same degree of freedom (i.e., electric dipole), similar with the ferroelectric-ferroelastic state in ferroelectrics where the polar and strain orders are both dipole related. As further revealed by the features of electrical and mechanical responses of the nanowires under external fields, such polar-toroidal coupling brings us an efficient cross control of the toroidal (polar) order by static (curled) electric field, as well as superior piezoelectric and piezotoroidal responses in the nanowires.


Large and Tunable Polar-Toroidal Coupling in Ferroelectric Composite Nanowires toward Superior Electromechanical Responses.

Chen WJ, Zheng Y, Wang B - Sci Rep (2015)

Schematics of the model system and the basic idea of this investigation.(a) A periodic (BaTiO3)m/(SrTiO3)n composite nanowire. (b) In the nanowire, the BaTiO3 region is under partial screening along one direction and open-circuit condition along the other directions. (i) A multi-order state with coexistence of polar and toroidal orders and (ii) cross coupling between toroidization g and static electric field EH, and between polarization P and curled electric field EC may be achieved.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4477413&req=5

f1: Schematics of the model system and the basic idea of this investigation.(a) A periodic (BaTiO3)m/(SrTiO3)n composite nanowire. (b) In the nanowire, the BaTiO3 region is under partial screening along one direction and open-circuit condition along the other directions. (i) A multi-order state with coexistence of polar and toroidal orders and (ii) cross coupling between toroidization g and static electric field EH, and between polarization P and curled electric field EC may be achieved.
Mentions: Using first-principles-derived simulations, here we show that (BaTiO3)m/(SrTiO3)n nanowires (Fig. 1a) exhibit a large and tunable polar-toroidal coupling, which can lead to fruitful dipole states (including those being purely polar, purely toroidal, both polar and toroidal, or distorted toroidal) and phase boundaries, due to a combining effect of the anisotropic electrostatic interaction of the nanowire, the SrTiO3-layer-modified electrostatic interaction and the multiphase ground state of BaTiO3 layer (Fig. 1b). In the formula (BaTiO3)m/(SrTiO3)n, m and n refer to the thickness, in unit cells, of the (001) BaTiO3 and (001) SrTiO3 layers, respectively. In the nanowires, the polar and toroidal orders are intimately coupled as they are both carried by the same degree of freedom (i.e., electric dipole), similar with the ferroelectric-ferroelastic state in ferroelectrics where the polar and strain orders are both dipole related. As further revealed by the features of electrical and mechanical responses of the nanowires under external fields, such polar-toroidal coupling brings us an efficient cross control of the toroidal (polar) order by static (curled) electric field, as well as superior piezoelectric and piezotoroidal responses in the nanowires.

Bottom Line: Particularly, a strong polar-toroidal coupling that is tunable by the SrTiO3-layer thickness, temperature, external strains and electric fields is found to exist in the nanowires, with the appearance of fruitful dipole states (including those being purely polar, purely toroidal, both polar and toroidal, or distorted toroidal) and phase boundaries.As a consequence, an efficient cross control of the toroidal (polar) order by static (curled) electric field, and superior piezoelectric and piezotoroidal responses, can be achieved in the nanowires.The result provides new insights into the collective dipole behaviors in nanowire systems.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China [2] Micro &Nano Physics and Mechanics Research Laboratory, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China.

ABSTRACT
The collective dipole behaviors in (BaTiO3)m/(SrTiO3)n composite nanowires are investigated based on the first-principles-derived simulations. It demonstrates that such nanowire systems exhibit intriguing dipole orders, due to the combining effect of the anisotropic electrostatic interaction of the nanowire, the SrTiO3-layer-modified electrostatic interaction and the multiphase ground state of BaTiO3 layer. Particularly, a strong polar-toroidal coupling that is tunable by the SrTiO3-layer thickness, temperature, external strains and electric fields is found to exist in the nanowires, with the appearance of fruitful dipole states (including those being purely polar, purely toroidal, both polar and toroidal, or distorted toroidal) and phase boundaries. As a consequence, an efficient cross control of the toroidal (polar) order by static (curled) electric field, and superior piezoelectric and piezotoroidal responses, can be achieved in the nanowires. The result provides new insights into the collective dipole behaviors in nanowire systems.

No MeSH data available.