Date:
Thu, 03/04/202512:00-13:30
Location:
Danciger B Building, Seminar room
Lecturer: Lior Kornblum, Andrew & Erna Viterbi Dept. of Electrical & Computer Engineering, Technion, Haifa
Abstract:
Electron correlation is responsible for countless interesting condensed matter phenomena.
Oxides with electron correlation provide an attractive testbed for many of those, where
coupling between the spin, charge and lattice degrees of freedom can be tweaked and
explored. Our work started with strontium vanadate (SrVO 3 ) as a simple test case of the
Mott-Hubbard type of correlated electronic structure. We harness advanced thin film
synthesis techniques to control the correlation strength by tuning the degree of orbital
overlap using picometer-scale lattice engineering. We illustrate how bandwidth control and
concurrent symmetry breaking can govern the electronic structure of this SrVO 3 model
system. This shows how tensile and compressive biaxial strain oppositely affect the SrVO 3 in-
plane and out-of-plane orbital occupancy, resulting in the partial alleviation of the orbital
degeneracy. The spectral weight redistribution under strain is derived and explained,
illustrating how tensile strain drives the system toward a Mott insulating state. The critical
role of the surface chemistry in this picture will be addressed. This picture, derived from a
simple and clean system, can shed light on other more complex examples.
Pivoting from the simple SrVO 3 system, we studied films of La 1-x Sr x VO 3 , a filling-controlled
Mott system where the number of free electrons and the electronic phase can be
manipulated by the composition. From this system, we crafted a back-gated (solid state)
field-effect device with a correlated, Mott channel. With this rudimentary device, we
demonstrate that with increasing the electron density in the electron channel, the resistance
actually increases. This behavior is explained by an increase in the correlation strength due
to the increase in electron-electron interaction. The effect on resistivity is ×10 larger than
the change in the electron density, and we show that it is actually as much as ×100 due to
screening of the field. We will discuss our vision for crafting this limited demonstrator into a
device that might be practical one day.
Abstract:
Electron correlation is responsible for countless interesting condensed matter phenomena.
Oxides with electron correlation provide an attractive testbed for many of those, where
coupling between the spin, charge and lattice degrees of freedom can be tweaked and
explored. Our work started with strontium vanadate (SrVO 3 ) as a simple test case of the
Mott-Hubbard type of correlated electronic structure. We harness advanced thin film
synthesis techniques to control the correlation strength by tuning the degree of orbital
overlap using picometer-scale lattice engineering. We illustrate how bandwidth control and
concurrent symmetry breaking can govern the electronic structure of this SrVO 3 model
system. This shows how tensile and compressive biaxial strain oppositely affect the SrVO 3 in-
plane and out-of-plane orbital occupancy, resulting in the partial alleviation of the orbital
degeneracy. The spectral weight redistribution under strain is derived and explained,
illustrating how tensile strain drives the system toward a Mott insulating state. The critical
role of the surface chemistry in this picture will be addressed. This picture, derived from a
simple and clean system, can shed light on other more complex examples.
Pivoting from the simple SrVO 3 system, we studied films of La 1-x Sr x VO 3 , a filling-controlled
Mott system where the number of free electrons and the electronic phase can be
manipulated by the composition. From this system, we crafted a back-gated (solid state)
field-effect device with a correlated, Mott channel. With this rudimentary device, we
demonstrate that with increasing the electron density in the electron channel, the resistance
actually increases. This behavior is explained by an increase in the correlation strength due
to the increase in electron-electron interaction. The effect on resistivity is ×10 larger than
the change in the electron density, and we show that it is actually as much as ×100 due to
screening of the field. We will discuss our vision for crafting this limited demonstrator into a
device that might be practical one day.