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Author |
Conti, S.; Saberi-Pouya, S.; Perali, A.; Virgilio, M.; Peeters, F.M.; Hamilton, A.R.; Scappucci, G.; Neilson, D. |
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Title |
Electron-hole superfluidity in strained Si/Ge type II heterojunctions |
Type |
A1 Journal article |
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Year  |
2021 |
Publication |
npj Quantum Materials |
Abbreviated Journal |
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Volume |
6 |
Issue |
1 |
Pages |
41 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Excitons are promising candidates for generating superfluidity and Bose-Einstein condensation (BEC) in solid-state devices, but an enabling material platform with in-built band structure advantages and scaling compatibility with industrial semiconductor technology is lacking. Here we predict that spatially indirect excitons in a lattice-matched strained Si/Ge bilayer embedded into a germanium-rich SiGe crystal would lead to observable mass-imbalanced electron-hole superfluidity and BEC. Holes would be confined in a compressively strained Ge quantum well and electrons in a lattice-matched tensile strained Si quantum well. We envision a device architecture that does not require an insulating barrier at the Si/Ge interface, since this interface offers a type II band alignment. Thus the electrons and holes can be kept very close but strictly separate, strengthening the electron-hole pairing attraction while preventing fast electron-hole recombination. The band alignment also allows a one-step procedure for making independent contacts to the electron and hole layers, overcoming a significant obstacle to device fabrication. We predict superfluidity at experimentally accessible temperatures of a few Kelvin and carrier densities up to similar to 6 x 10(10) cm(-2), while the large imbalance of the electron and hole effective masses can lead to exotic superfluid phases. |
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Wos |
000642904200001 |
Publication Date |
2021-04-23 |
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ISSN |
2397-4648 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
5 |
Open Access |
OpenAccess |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:178226 |
Serial |
6984 |
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Author |
Du, K.; Guo, L.; Peng, J.; Chen, X.; Zhou, Z.-N.; Zhang, Y.; Zheng, T.; Liang, Y.-P.; Lu, J.-P.; Ni, Z.-H.; Wang, S.-S.; Van Tendeloo, G.; Zhang, Z.; Dong, S.; Tian, H. |
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Title |
Direct visualization of irreducible ferrielectricity in crystals |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
npj Quantum Materials |
Abbreviated Journal |
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Volume |
5 |
Issue |
1 |
Pages |
49-7 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
In solids, charge polarity can one-to-one correspond to spin polarity phenomenologically, e.g., ferroelectricity/ferromagnetism, antiferroelectricity/antiferromagnetism, and even dipole-vortex/magnetic-vortex, but ferrielectricity/ferrimagnetism kept telling a disparate story in microscopic level. Since the definition of a charge dipole involves more than one ion, there may be multiple choices for a dipole unit, which makes most ferrielectric orders equivalent to ferroelectric ones, i.e., this ferrielectricity is not necessary to be a real independent branch of polarity. In this work, by using the spherical aberration-corrected scanning transmission electron microscope, we visualize a nontrivial ferrielectric structural evolution in BaFe2Se3, in which the development of two polar sub-lattices is out-of-sync, for which we term it as irreducible ferrielectricity. Such irreducible ferrielectricity leads to a non-monotonic behavior for the temperature-dependent polarization, and even a compensation point in the ordered state. Our finding unambiguously distinguishes ferrielectrics from ferroelectrics in solids. |
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Wos |
000551499400001 |
Publication Date |
2020-07-23 |
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2397-4648 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
OpenAccess |
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Notes |
; We acknowledge the National Natural Science Foundation of China (Grant Nos. 11834002, 11674055, and 11234011), National Key R&D Program of China 2017YFB0703100, and the 111 Project (Grant No. B16042). K.D. acknowledges the China Scholarship Council (CSC, No.201806320230) for sponsorship and 2019 Zhejiang University Academic Award for Outstanding Doctoral Candidates. We thank Prof. Fang Lin for providing guidance on calculating atoms position and Dr. Andrew Studer for performing neutron powder diffraction. We thank Prof. Sang-Wook Cheong, Prof. Zhigao Sheng, Prof. Qianghua Wang, Prof. Meng Wang, Prof. Renkui Zheng, Prof. Takuya Aoyama, Dr. Zhibo Yan, and Dr. Meifeng Liu for valuable discussion and/or technical help during measurements. ; |
Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:171225 |
Serial |
6486 |
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Author |
Yasui, Y.; Lahabi, K.; Fernández Becerra, V.; Fermin, R.; Anwar, M.S.; Yonezawa, S.; Terashima, T.; Milošević, M.V.; Aarts, J.; Maeno, Y. |
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Title |
Spontaneous emergence of Josephson junctions in homogeneous rings of single-crystal Sr₂RuO₄ |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
npj Quantum Materials |
Abbreviated Journal |
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Volume |
5 |
Issue |
1 |
Pages |
21-28 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
The chiral p-wave order parameter in Sr2RuO4 would make it a special case amongst the unconventional superconductors. A consequence of this symmetry is the possible existence of superconducting domains of opposite chirality. At the boundary of such domains, the locally suppressed condensate can produce an intrinsic Josephson junction. Here, we provide evidence of such junctions using mesoscopic rings, structured from Sr2RuO4 single crystals. Our order parameter simulations predict such rings to host stable domain walls across their arms. This is verified with transport experiments on loops, with a sharp transition at 1.5 K, which show distinct critical current oscillations with periodicity corresponding to the flux quantum. In contrast, loops with broadened transitions at around 3 K are void of such junctions and show standard Little-Parks oscillations. Our analysis demonstrates the junctions are of intrinsic origin and makes a compelling case for the existence of superconducting domains. |
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Wos |
000525721000001 |
Publication Date |
2020-04-09 |
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Abbreviated Series Title |
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ISSN |
2397-4648 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
10 |
Open Access |
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Notes |
; The authors would like to thank S. Goswami, A. Singh, M. Kupryianov, S. Bakurskiy, J. Jobst, T. Nakamura, K. Adachi, Y. Liu, and Y. Asano for valuable discussions and comments, and F. Hubler, Y. Nakamura, and Y. Yamaoka for their technical contribution. This work was supported by a Grant-in-Aid for Scientific Research on Innovative Areas “Topological Materials Science” (KAKENHI Grant Nos. JP15H05852, JP15K21717, JP15H05851), JSPS-EPSRC Core-to-Core program (A. Advanced Research Network), JSPS research fellow (KAKENHI Grant No. JP16J10404), Grant-in-Aid JSPS KAKENHI JP26287078 and JP17H04848, and the Netherlands Organisation for Scientific Research (NWO/OCW), as part of the Frontiers of Nanoscience program. V.F.B. acknowledges support from the Foundation for Polish Science through the IRA Programme co-financed by EU within SG OP. ; |
Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:168553 |
Serial |
6613 |
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