High resolution studies of quantum melting of field-induced Wigner crystals
Oral-In-person
Abstract
Abstract:
Classical melting of a two-dimensional crystal is described by the KTHNY theory1–3. Whether melting driven by quantum parameters obeys the same framework remains open. We will address this by directly imaging field-induced Wigner crystals as they cross into liquids, including fractional quantum Hall (FQH) liquids. Previous study has already imaged such crystal at high magnetic fields4. Here, we will use millikelvin, high resolution STM to visualize quantum melting driven by carrier density in Bernal-stacked bilayer graphene. Our observations indicate that the usual topological defect picture breaks down, pointing to a mechanism beyond KTHNY. We find distinct behaviors for melting into a normal liquid versus into FQH liquids.
References:
1. Kosterlitz, J. M. & Thouless, D. J. Ordering, metastability and phase transitions in two-dimensional systems. J. Phys. C Solid State Phys. 6, 1181 (1973).
2. Halperin, B. I. Theory of Two-Dimensional Melting. Phys. Rev. Lett. 41, 121–124 (1978).
3. Young, A. P. Melting and the vector Coulomb gas in two dimensions. Phys. Rev. B 19, 1855–1866 (1979).
4. Tsui, Y.-C. et al. Direct observation of a magnetic-field-induced Wigner crystal. Nature 628, 287–292 (2024).
Classical melting of a two-dimensional crystal is described by the KTHNY theory1–3. Whether melting driven by quantum parameters obeys the same framework remains open. We will address this by directly imaging field-induced Wigner crystals as they cross into liquids, including fractional quantum Hall (FQH) liquids. Previous study has already imaged such crystal at high magnetic fields4. Here, we will use millikelvin, high resolution STM to visualize quantum melting driven by carrier density in Bernal-stacked bilayer graphene. Our observations indicate that the usual topological defect picture breaks down, pointing to a mechanism beyond KTHNY. We find distinct behaviors for melting into a normal liquid versus into FQH liquids.
References:
1. Kosterlitz, J. M. & Thouless, D. J. Ordering, metastability and phase transitions in two-dimensional systems. J. Phys. C Solid State Phys. 6, 1181 (1973).
2. Halperin, B. I. Theory of Two-Dimensional Melting. Phys. Rev. Lett. 41, 121–124 (1978).
3. Young, A. P. Melting and the vector Coulomb gas in two dimensions. Phys. Rev. B 19, 1855–1866 (1979).
4. Tsui, Y.-C. et al. Direct observation of a magnetic-field-induced Wigner crystal. Nature 628, 287–292 (2024).
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Presenters
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Yen-Chen Tsui
- Princeton University