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TT: Fachverband Tiefe Temperaturen

TT 78: Quantum Dots and Point Contacts (joint session TT/HL)

TT 78.6: Vortrag

Donnerstag, 12. März 2026, 12:15–12:30, HSZ/0101

Electromigrated palladium nano-contacts: formation of atomic contacts and non linear current-voltage characteristics — •Samanwita Biswas¹, Thomas Hultzsch¹, Marcel Strohmeier², Elke Scheer², and Regina Hoffmann-Vogel¹ — ¹Institute of Physics and Astronomy, University of Potsdam — ²Department of Physics, University of Konstanz

We investigate the electronic transport properties of atomic-size Pd contacts fabricated by electromigration (EM) of lithographically defined nano-constrictions, at room temperature in different environments. In particular we study changes in the conductance upon EM with a focus on possible shell effects [1]. By systematic analysis of a large number of data sets in the conductance range up to ∼ 10 G₀ (with the conductance quantum G₀ = 2e²/h), we identify preferential conductance values and compare these with the ones expected for shell closure in multivalent metals. For contacts with G 5 G₀, the current-voltage characteristics often become nonlinear on a scale of few 100mV; we discuss this observation with respect to structural changes during the thinning process of EM. By monitoring the smallest conductances, we often identify a decrement of resistance inside a cycle, opposite to the overall trend, indicating the transition to the ballistic regime. Our results suggest that metallic few atomic contacts of Pd, despite being more reactive than noble metals, can be stabilized even at room temperature.
[1] Mares & van Ruitenbeek, Phys. Rev. B 72, 205402 (2005)

Keywords: atomic contact; Electromigration; Quantum conductance; Electron beam lithography; Non-linear transport