Dennis Huang

Monolayer FeSe on SrTiO3

Epitaxial engineering of solid state heterointerfaces is a leading avenue to realizing enhanced or novel electronic states of matter. As a recent example, bulk FeSe is an unconventional superconductor with a modest transition temperature (Tc) of 9 K. However, when a single atomic layer of FeSe is grown on SrTiO3, its Tc can skyrocket by an order of magnitude to 65 K or 109 K. Since this discovery in 2012, efforts to reproduce, understand, and extend these findings continue to draw both excitement and scrutiny. In this review, we first present a critical survey of experimental measurements performed using a wide range of techniques. We then turn to the open question of microscopic mechanisms of superconductivity. We examine contrasting indications for both phononic (conventional) and magnetic/orbital (unconventional) means of electron pairing, as well as speculations about whether they could work cooperatively to boost Tc in a monolayer of FeSe.

Revealing the Empty-State Electronic Structure of Single-Unit-Cell FeSe/SrTiO3

We use scanning tunneling spectroscopy to investigate the filled and empty electronic states of superconducting single-unit-cell FeSe deposited on SrTiO3(001). We map the momentum-space band structure by combining quasiparticle interference imaging with decay length spectroscopy. In addition to quantifying the filled-state bands, we discover a Γ-centered electron pocket 75 meV above the Fermi energy. Our density functional theory calculations show the orbital nature of empty states at Γ and explain how the Se height is a key tuning parameter of their energies, with broad implications for electronic properties.

Nanoscale surface element identification and dopant homogeneity in the high-\(T_{c}\) superconductor \(Pr_xCa_{1−x}Fe_2As_2\)

We use scanning tunneling microscopy to determine the surface structure and dopant distribution in Pr

Nanoscale interplay of strain and doping in a high-temperature superconductor

_x

Bounds on nanoscale nematicity in single-layerFeSe/SrTiO3

Ca

Electric field tuning of band offsets in transition metal dichalcogenides

_{1-x}

Etching of Cr tips for scanning tunneling microscopy of cleavable oxides

Fe

Imaging of Quantum Materials

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Dumbbell Defects in FeSe Films: A Scanning Tunneling Microscopy and First-Principles Investigation

As

A Tale of Two Domes

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