Mott Insulator Ca<sub>2</sub>RuO<sub>4</sub> under External Electric Field
We have investigated the structural, electronic and magnetic properties of the Mott insulator Ca<sub>2</sub>RuO<sub>4</sub> under the application of a static external electric field in two regimes: bulk systems at small fields and thin films at large electric fields. Ca<su...
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MDPI AG
2022-09-01
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| Online Access: | https://www.mdpi.com/1996-1944/15/19/6657 |
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| author | Giuseppe Cuono Carmine Autieri |
| author_facet | Giuseppe Cuono Carmine Autieri |
| author_sort | Giuseppe Cuono |
| collection | DOAJ |
| description | We have investigated the structural, electronic and magnetic properties of the Mott insulator Ca<sub>2</sub>RuO<sub>4</sub> under the application of a static external electric field in two regimes: bulk systems at small fields and thin films at large electric fields. Ca<sub>2</sub>RuO<sub>4</sub> presents S- and L-Pbca phases with short and long c lattice constants and with large and small band gaps, respectively. Using density functional perturbation theory, we have calculated the Born effective charges as response functions. Once we break the inversion symmetry by off-centering the Ru atoms, we calculate the piezoelectric properties of the system that suggest an elongation of the system under an electric field. Finally, we investigated a four-unit cell slab in larger electric fields, and we found insulator–metal transitions induced by the electric field. By looking at the local density of states, we have found that the gap gets closed on surface layers while the rest of the sample is insulating. Correlated to the electric-field-driven gap closure, there is an increase in the lattice constant c. Regarding the magnetic properties, we have identified two phase transitions in the magnetic moments with one surface that gets completely demagnetized at the largest field investigated. In all cases, the static electric field increases the lattice constant c and reduces the band gap of Ca<sub>2</sub>RuO<sub>4</sub>, playing a role in the competition between the L-phase and the S-phase. |
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| id | doaj.art-87d1f2fc96e54320b017ebbc62238ebb |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-09T21:31:33Z |
| publishDate | 2022-09-01 |
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| series | Materials |
| spelling | doaj.art-87d1f2fc96e54320b017ebbc62238ebb2023-11-23T20:54:32ZengMDPI AGMaterials1996-19442022-09-011519665710.3390/ma15196657Mott Insulator Ca<sub>2</sub>RuO<sub>4</sub> under External Electric FieldGiuseppe Cuono0Carmine Autieri1International Research Centre Magtop, Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, PolandInternational Research Centre Magtop, Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, PolandWe have investigated the structural, electronic and magnetic properties of the Mott insulator Ca<sub>2</sub>RuO<sub>4</sub> under the application of a static external electric field in two regimes: bulk systems at small fields and thin films at large electric fields. Ca<sub>2</sub>RuO<sub>4</sub> presents S- and L-Pbca phases with short and long c lattice constants and with large and small band gaps, respectively. Using density functional perturbation theory, we have calculated the Born effective charges as response functions. Once we break the inversion symmetry by off-centering the Ru atoms, we calculate the piezoelectric properties of the system that suggest an elongation of the system under an electric field. Finally, we investigated a four-unit cell slab in larger electric fields, and we found insulator–metal transitions induced by the electric field. By looking at the local density of states, we have found that the gap gets closed on surface layers while the rest of the sample is insulating. Correlated to the electric-field-driven gap closure, there is an increase in the lattice constant c. Regarding the magnetic properties, we have identified two phase transitions in the magnetic moments with one surface that gets completely demagnetized at the largest field investigated. In all cases, the static electric field increases the lattice constant c and reduces the band gap of Ca<sub>2</sub>RuO<sub>4</sub>, playing a role in the competition between the L-phase and the S-phase.https://www.mdpi.com/1996-1944/15/19/6657Mott insulatortransition metal oxideselectric fieldborn effective chargesdensity functional theorypiezoelectric tensor |
| spellingShingle | Giuseppe Cuono Carmine Autieri Mott Insulator Ca<sub>2</sub>RuO<sub>4</sub> under External Electric Field Materials Mott insulator transition metal oxides electric field born effective charges density functional theory piezoelectric tensor |
| title | Mott Insulator Ca<sub>2</sub>RuO<sub>4</sub> under External Electric Field |
| title_full | Mott Insulator Ca<sub>2</sub>RuO<sub>4</sub> under External Electric Field |
| title_fullStr | Mott Insulator Ca<sub>2</sub>RuO<sub>4</sub> under External Electric Field |
| title_full_unstemmed | Mott Insulator Ca<sub>2</sub>RuO<sub>4</sub> under External Electric Field |
| title_short | Mott Insulator Ca<sub>2</sub>RuO<sub>4</sub> under External Electric Field |
| title_sort | mott insulator ca sub 2 sub ruo sub 4 sub under external electric field |
| topic | Mott insulator transition metal oxides electric field born effective charges density functional theory piezoelectric tensor |
| url | https://www.mdpi.com/1996-1944/15/19/6657 |
| work_keys_str_mv | AT giuseppecuono mottinsulatorcasub2subruosub4subunderexternalelectricfield AT carmineautieri mottinsulatorcasub2subruosub4subunderexternalelectricfield |