The focus of this talk will be the creation of a new tunable microwave dielectric with record performance at frequencies up to 120 GHz. This is achieved by energizing a low-loss dielectric host with a highly tunable ground state arising from the emergence of a local ferroelectric instability. In contrast to traditional methods of modifying ferroelectrics—doping or strain—in this rather unique system increasing the separation between the (SrO)2 planes bolsters the local ferroelectric instability. This new control parameter, n, can be exploited to achieve a figure of merit at room temperature that surpasses all known tunable microwave dielectrics. I will end by showing a few results from a new direction we* have embarked on—the combination of reactive molecularbeam epitaxy (MBE) to create oxide structures customized at the atomic-layer level with the in situ measurement of their electronic structure by angle-resolved photoemission spectroscopy (ARPES).

* = in collaboration with the group of Kyle Shen (Physics, Cornell)

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