PhD thesis defense. Non-linear transport in chiral Tellurium: from fundamentals to applications

Electronic transport has long been described by Ohm’s law, which establishes a linear relationship between the applied electric current and the resulting voltage. This linearity is intimately linked to the presence of spatial inversion symmetry in conventional materials, which constrains the allowed form of the current–voltage response. However, in systems lacking inversion symmetry, these constraints are relaxed, and non-linear electrical transport becomes allowed. In such non-centrosymmetric materials, the voltage can exhibit a quadratic dependence on the applied current, giving rise to a range of unconventional physical phenomena with promising applications in electronics, spintronics, and energy harvesting.

 

Materials that intrinsically break spatial inversion symmetry, and particularly those with chiral crystal structures that also lack mirror symmetry, provide a unique platform for investigating non-linear transport effects. Among these, elemental tellurium (Te) stands out as an exemplary system. Te crystallizes in a trigonal structure that exists in two enantiomorphic forms (left- and right-handed), offering an ideal model to probe the roles of structural chirality and broken inversion symmetry in electronic transport. Its semiconducting character, along with its sensitivity to electrostatic gating and external magnetic fields, further enhances its suitability for studying tunable non-linear electronic responses.

 

This thesis investigates the fundamental connection between crystal symmetry and non-linear transport phenomena in chiral Te. By combining symmetry analysis, device fabrication, and low-temperature magnetotransport measurements, this work aims to uncover both the underlying physical mechanisms and the potential for novel device functionalities enabled by non-linear electronic transport in chiral systems.