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Positive and Negative Pressure Regimes in Anisotropically Strained V2O3 Films
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2023-05-19 , DOI: 10.1002/adfm.202211801
Eti Barazani 1 , Dip Das 1 , Chubin Huang 1 , Abhishek Rakshit 1 , Cecile Saguy 2 , Pavel Salev 3 , Javier del Valle 4 , Maytal Caspary Toroker 1 , Ivan K. Schuller 5 , Yoav Kalcheim 1
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2023-05-19 , DOI: 10.1002/adfm.202211801
Eti Barazani 1 , Dip Das 1 , Chubin Huang 1 , Abhishek Rakshit 1 , Cecile Saguy 2 , Pavel Salev 3 , Javier del Valle 4 , Maytal Caspary Toroker 1 , Ivan K. Schuller 5 , Yoav Kalcheim 1
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The metal-insulator phase transitions in V2O3 are considered archetypal manifestations of Mott physics. Despite decades of research, the effects of doping, pressure, and anisotropic strains on the transitions are still debated. To understand how these parameters control the transitions, anisotropically strained pure V2O3 films are explored with nearly the same contraction along the c-axis, but different degrees of ab-plane expansion. With small ab-plane expansion, the films behave similar to bulk V2O3 under hydrostatic pressure. However, with large ab-plane expansion, the films are driven into the “negative pressure” regime, similar to that of Cr-doped V2O3, exhibiting clear coexistence of paramagnetic insulator and paramagnetic metal phases between 180–500 K. This shows that c-axis contraction alone, or an increase in c/a ratio is insufficient for inducing “negative pressure” effects. Actually, c-axis contraction alone destabilizes the two insulating phases of V2O3, whereas a-axis expansion tends to stabilize them. The effects of strain are modeled using density functional theory providing good agreement with experimental results. The findings show that chemical pressure alone cannot account for the phase diagram of (V1−xCrx)2O3. This work enables to manipulate a Mott transition above room temperature, thereby expanding the opportunities for applications of V2O3 in novel electronics.
中文翻译：
各向异性应变 V2O3 薄膜中的正压和负压状态
V 2 O 3中的金属-绝缘体相变被认为是莫特物理学的典型表现。尽管经过了数十年的研究，掺杂、压力和各向异性应变对转变的影响仍然存在争议。为了了解这些参数如何控制转变，我们探索了各向异性应变的纯 V 2 O 3薄膜，沿c轴几乎具有相同的收缩，但 ab 平面膨胀程度不同。由于 ab 平面膨胀较小，薄膜在静水压力下的表现类似于块状 V 2 O 3。然而，随着 ab 平面的较大膨胀，薄膜被驱动进入“负压”状态，类似于 Cr 掺杂的 V2 O 3，在180-500 K之间表现出顺磁绝缘体和顺磁金属相的明显共存。这表明单独的c轴收缩或c/a比率的增加不足以引起“负压”效应。实际上，c轴收缩本身就会使 V 2 O 3的两个绝缘相不稳定，而a轴膨胀往往会使它们稳定。使用密度泛函理论对应变的影响进行建模，与实验结果非常吻合。研究结果表明，仅化学压力无法解释 (V 1−x Cr x ) 2 O 3的相图。这项工作能够在室温以上操纵莫特转变，从而扩大 V 2 O 3在新型电子学中的应用机会。
更新日期：2023-05-19
中文翻译：
各向异性应变 V2O3 薄膜中的正压和负压状态
V 2 O 3中的金属-绝缘体相变被认为是莫特物理学的典型表现。尽管经过了数十年的研究，掺杂、压力和各向异性应变对转变的影响仍然存在争议。为了了解这些参数如何控制转变，我们探索了各向异性应变的纯 V 2 O 3薄膜，沿c轴几乎具有相同的收缩，但 ab 平面膨胀程度不同。由于 ab 平面膨胀较小，薄膜在静水压力下的表现类似于块状 V 2 O 3。然而，随着 ab 平面的较大膨胀，薄膜被驱动进入“负压”状态，类似于 Cr 掺杂的 V2 O 3，在180-500 K之间表现出顺磁绝缘体和顺磁金属相的明显共存。这表明单独的c轴收缩或c/a比率的增加不足以引起“负压”效应。实际上，c轴收缩本身就会使 V 2 O 3的两个绝缘相不稳定，而a轴膨胀往往会使它们稳定。使用密度泛函理论对应变的影响进行建模，与实验结果非常吻合。研究结果表明，仅化学压力无法解释 (V 1−x Cr x ) 2 O 3的相图。这项工作能够在室温以上操纵莫特转变，从而扩大 V 2 O 3在新型电子学中的应用机会。
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