Instytut Podstawowych Problemów Techniki
Polskiej Akademii Nauk


Xiaofeng Xu

Ostatnie publikacje
1.  Chudziński P., Berben M., Xu X., Wakeham N., Bernáth B., Duffy C., Hinlopen R., Hsu Y., Wiedmann S., Tinnemans P., Jin R., Greenblatt M., Hussey N., Emergent symmetry in a low-dimensional superconductor on the edge of Mottness, Science, ISSN: 0036-8075, DOI: 10.1126/science.abp8948, Vol.382, pp.3-5, 2023

Upon cooling, condensed-matter systems typically transition into states of lower symmetry. The converse—i.e., the emergence of higher symmetry at lower temperatures—is extremely rare. In this work, we show how an unusually isotropic magnetoresistance in the highly anisotropic, one-dimensional conductor Li0.9Mo6O17 and its temperature dependence can be interpreted as a renormalization group (RG) flow toward a so-called separatrix. This approach is equivalent to an emergent symmetry in the system. The existence of two distinct ground states, Mott insulator and superconductor, can then be traced back to two opposing RG trajectories. By establishing a direct link between quantum field theory and an experimentally measurable quantity, we uncover a path through which emergent symmetry might be identified in other candidate materials

Afiliacje autorów:
Chudziński P. - IPPT PAN
Berben M. - inna afiliacja
Xu X. - inna afiliacja
Wakeham N. - inna afiliacja
Bernáth B. - inna afiliacja
Duffy C. - inna afiliacja
Hinlopen R. - inna afiliacja
Hsu Y. - inna afiliacja
Wiedmann S. - inna afiliacja
Tinnemans P. - inna afiliacja
Jin R. - inna afiliacja
Greenblatt M. - inna afiliacja
Hussey N. - inna afiliacja
2.  Chen R., Xue Yafei ., Xu X., Yang H., Qiu T., Shui Lingling ., Wang Xin ., Zhou G., Giersig M., Pidot S., Hutchison J.A ., Akinoglu E.M., Lithography-free synthesis of periodic, vertically-aligned, multi-walled carbon nanotube arrays, NANOTECHNOLOGY, ISSN: 0957-4484, DOI: 10.1088/1361-6528/ac345a, Vol.33, No.065304 , pp.1-9, 2021

Until now, the growth of periodic vertically aligned multi-walled carbon nanotube (VA-
MWCNT) arrays was dependent on at least one lithography step during fabrication. Here, we demonstrate a lithography-free fabrication method to grow hexagonal arrays of self-standing VA-MWCNTs with tunable pitch and MWCNT size. The MWCNTs are synthesized by plasma enhanced chemical vapor deposition (PECVD) from Ni catalyst particles. Template guided dewetting of a thin Ni film on a hexagonally close-packed silica particle monolayer provides periodically distributed Ni catalyst particles as seeds for the growth of the periodic MWCNT arrays. The diameter of the silica particles directly controls the pitch of the periodic VA-MWCNT arrays from 600 nm to as small as 160 nm. The diameter and length of the individual MWCNTs can also be readily adjusted and are a function of the Ni particle size and PECVD time. This unique method of lithography-free growth of periodic VA-MWCNT arrays can be utilized for the fabrication of large-scale biomimetic materials

Słowa kluczowe:
periodic, ithography free, nanofabrication, template guided, vertically-aligned multi- walled carbon nanotubes, self-standing

Afiliacje autorów:
Chen R. - inna afiliacja
Xue Yafei . - South China Normal University (CN)
Xu X. - inna afiliacja
Yang H. - South China Normal University (CN)
Qiu T. - inna afiliacja
Shui Lingling . - South China Normal University (CN)
Wang Xin . - inna afiliacja
Zhou G. - South China Normal University (CN)
Giersig M. - IPPT PAN
Pidot S. - inna afiliacja
Hutchison J.A . - inna afiliacja
Akinoglu E.M. - University of Melbourne (AU)
3.  Lu J., Xu X., Greenblatt M., Jin R., Tinnemans P., Licciardello S., van Delft M.R., Buhot J., Chudziński P., Hussey N.E., Emergence of a real-space symmetry axis in the magnetoresistance of the one-dimensional conductor Li0.9Mo6O17, Science Advances, ISSN: 2375-2548, DOI: 10.1126/sciadv.aar8027, Vol.5, No.7, pp.eaar8027-1-7, 2019

We report on an emerging symmetry axis in the magnetoresistance of bulk single crystals of quasi–one-dimensional Li0.9Mo6O17 below Tmin = 25 K, the temperature at which the electrical resistivity experiences a minimum. Detailed angle-dependent magnetoresistance sweeps reveal that this symmetry axis is induced by the development of a negative magnetoresistance, which is suppressed only for magnetic fields oriented along the poles of the MoO6 octahedra that form the conducting chains. We show that this unusual negative magnetoresistance is consistent with the melting of dark excitons, composed of previously omitted orbitals within the t2g manifold that order below Tmin. The unveiled symmetry axis in directional magnetic fields not only provides evidence for the crystallization of these dark excitons but also sheds new light on the long-standing mystery of the metal-insulator transition in Li0.9Mo6O17.

Afiliacje autorów:
Lu J. - inna afiliacja
Xu X. - inna afiliacja
Greenblatt M. - inna afiliacja
Jin R. - inna afiliacja
Tinnemans P. - inna afiliacja
Licciardello S. - inna afiliacja
van Delft M.R. - inna afiliacja
Buhot J. - inna afiliacja
Chudziński P. - inna afiliacja
Hussey N.E. - inna afiliacja

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