Electronic Localization in CaVO3 Films via Bandwidth Control
Daniel E. McNally, Xingye Lu, Jonathan Pelliciari, Sophie Beck, Marcus Dantz, Muntaser Naamneh, Tian Shang, Marisa Medarde, Christof W. Schneider, Vladimir N. S… 展开作者
Daniel E. McNally, Xingye Lu, Jonathan Pelliciari, Sophie Beck, Marcus Dantz, Muntaser Naamneh, Tian Shang, Marisa Medarde, Christof W. Schneider, Vladimir N. Strocov, Ekaterina V. Pomjakushina, Claude Ederer, Milan Radovic, Thorsten Schmitt
Understanding and controlling the electronic structure of thin layers of quantum materials is a crucial first step towards designing heterostructures where new phases and phenomena, including the metal-insulator transition (MIT), emerge. Here, we demonstrate control of the MIT via tuning electronic bandwidth and local site environment through selection of the number of atomic layers deposited. We take CaVO3, a correlated metal in its bulk form that has only a single electron in its V4+ 3d manifold, as a representative example. We find that thick films and ultrathin films (6 unit cells, uc, and below) are metallic and insulating, respectively, while a 10 uc CaVO3 film exhibits a clear thermal MIT. Our combined X-ray absorption spectroscopy and resonant inelastic x-ray scattering (RIXS) study reveals that the thickness-induced MIT is triggered by electronic bandwidth reduction and local moment formation from V3+ ions, that are both a consequence of the thickness confinement. The thermal MIT in our 10 uc CaVO3 film exhibits similar changes in the RIXS response to that of the thickness-induced MIT in terms of reduction of bandwidth and V 3d - O 2p hybridization.
Electrical-transport characteristics of as-grown and oxygen-reduced La$_{0.7}$Ce$_{0.3}$MnO$_3$ films: calculation of hopping energies, Mn valences, and carrier localization lengths
目前，铈掺杂的LaMnO $_3$被生动地讨论为电子掺杂的对应原型，以充分建立的空穴掺杂的混合价锰氧化物。在此，比较在SrTiO $_3$单晶衬底上生长的不同厚度、CeO $_3$相分离程度和氧缺乏的La $_{0.7}$ Ce $_{0.3}$ MnO $_3$薄膜的电阻-相对电阻-相对电阻。从300~ 90 K的温度（R vs. T）行为。当薄膜厚度在10~ 100 nm范围内变化时，外延应变对电输运的影响很小，而CeO $_2$团簇的存在和氧的缺乏则完全改变了跳跃机制的类型.这是通过拟合各自的\textit{R-T}曲线与三种不同的传输模型（绝热极化子跳跃，莫特可变范围跳跃，埃夫罗斯-什克洛夫斯基可变范围跳跃），这是常用的混合价锰氧化物。几个特征的输运参数，如跳跃能量，载流子局域化长度，以及Mn价从拟合程序推导出来。
Electronic localization on the structural inhomogeneities formed due to Bi and Te deficiency in the MBE grown films of AFM topological insulator MnBi2Te4: Evidence from spectroscopic ellipsometry and infrared studies
