1
|
High output mode-locked laser empowered by defect regulation in 2D Bi2O2Se saturable absorber. Nat Commun 2022; 13:3855. [PMID: 35790761 PMCID: PMC9256711 DOI: 10.1038/s41467-022-31606-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 06/16/2022] [Indexed: 12/17/2022] Open
Abstract
AbstractAtomically thin Bi2O2Se has emerged as a novel two-dimensional (2D) material with an ultrabroadband nonlinear optical response, high carrier mobility and excellent air stability, showing great potential for the realization of optical modulators. Here, we demonstrate a femtosecond solid-state laser at 1.0 µm with Bi2O2Se nanoplates as a saturable absorber (SA). Upon further defect regulation in 2D Bi2O2Se, the average power of the mode-locked laser is improved from 421 mW to 665 mW, while the pulse width is decreased from 587 fs to 266 fs. Moderate Ar+ plasma treatments are employed to precisely regulate the O and Se defect states in Bi2O2Se nanoplates. Nondegenerate pump-probe measurements show that defect engineering effectively accelerates the trapping rate and defect-assisted Auger recombination rate of photocarriers. The saturation intensity is improved from 3.6 ± 0.2 to 12.8 ± 0.6 MW cm−2 after the optimized defect regulation. The enhanced saturable absorption and ultrafast carrier lifetime endow the high-performance mode-locked laser with both large output power and short pulse duration.
Collapse
|
2
|
Minohara M, Hase I, Aiura Y. Characteristic Electronic Structure of SnO Film Showing High Hole Mobility. J Phys Chem Lett 2022; 13:1165-1171. [PMID: 35084204 DOI: 10.1021/acs.jpclett.1c04182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Actual knowledge of the intrinsic electronic characteristics of p-type oxide semiconductors should help guide the design of innovative electronic devices. The electronic characteristics of oxide semiconductors in thin-film form potentially differ from those in the bulk form owing to lattice strain. In this Letter, we report on the empirical band structure of stannous oxide (SnO) film, which has been shown to have a higher hole mobility than the theoretically expected values for SnO in the bulk form. In vacuo angle-resolved photoemission spectroscopy measurements reveal that the uppermost valence band is anisotropic between the out-of-plane and in-plane directions, and more dispersive than the theoretical predictions. Our findings unveil the underlying mechanism of the semiconductor properties of SnO films and suggest a suitable device structure based on the electronic characteristics.
Collapse
Affiliation(s)
- Makoto Minohara
- Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| | - Izumi Hase
- Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| | - Yoshihiro Aiura
- Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| |
Collapse
|
3
|
Bang J, Park J, Lee K, Kim M, Kyung W, Denlinger JD, Kim Y, Lee YH, Kim C, Kim SW. Antiperovskite Gd 3 SnC: Unusual Coexistence of Ferromagnetism and Heavy Fermions in Gd Lattice. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2102958. [PMID: 34319623 DOI: 10.1002/adma.202102958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/08/2021] [Indexed: 06/13/2023]
Abstract
Inverted structures of common crystal lattices, referred to as antistructures, are rare in nature due to their thermodynamic constraints imposed by the switched cation and anion positions in reference to the original structure. However, a stable antistructure formed with mixed bonding characters of constituent elements in unusual valence states can provide unexpected material properties. Here, a heavy-fermion behavior of ferromagnetic gadolinium lattice in Gd3 SnC antiperovskite is reported, contradicting the common belief that ferromagnetic gadolinium cannot be a heavy-fermion system due to the deep energy level of localized 4f-electrons. The specific heat shows an unusually large Sommerfeld coefficient of ≈1114 mJ mol-1 K-2 with a logarithmic behavior of non-Fermi-liquid state. It is demonstrated that the heavy-fermion behavior in the non-Fermi-liquid state appears to arise from the hybridized electronic states of gadolinium 5d-electrons participating in metallic GdGd and covalent GdC bonds. These results accentuate the unusual chemical bonds in CGd6 octahedra with the dual characters of gadolinium 5d-electrons for the emergence of heavy fermions.
Collapse
Affiliation(s)
- Joonho Bang
- Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jongho Park
- Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Kimoon Lee
- Department of Physics, Kunsan National University, Gunsan, 54150, Republic of Korea
| | - Minsoo Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Wonshik Kyung
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jonathan D Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yeongkwan Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
- Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, 16419, Republic of Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sung Wng Kim
- Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, 16419, Republic of Korea
| |
Collapse
|
4
|
Quantum transport evidence of Weyl fermions in an epitaxial ferromagnetic oxide. Nat Commun 2020; 11:4969. [PMID: 33037206 PMCID: PMC7547107 DOI: 10.1038/s41467-020-18646-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 09/06/2020] [Indexed: 11/13/2022] Open
Abstract
Magnetic Weyl semimetals have novel transport phenomena related to pairs of Weyl nodes in the band structure. Although the existence of Weyl fermions is expected in various oxides, the evidence of Weyl fermions in oxide materials remains elusive. Here we show direct quantum transport evidence of Weyl fermions in an epitaxial 4d ferromagnetic oxide SrRuO3. We employ machine-learning-assisted molecular beam epitaxy to synthesize SrRuO3 films whose quality is sufficiently high to probe their intrinsic transport properties. Experimental observation of the five transport signatures of Weyl fermions—the linear positive magnetoresistance, chiral-anomaly-induced negative magnetoresistance, π phase shift in a quantum oscillation, light cyclotron mass, and high quantum mobility of about 10,000 cm2V−1s−1—combined with first-principles electronic structure calculations establishes SrRuO3 as a magnetic Weyl semimetal. We also clarify the disorder dependence of the transport of the Weyl fermions, which gives a clear guideline for accessing the topologically nontrivial transport phenomena. Despite various predictions, the evidence of Weyl fermions in oxide materials remains elusive. Here, the authors show evidence of Weyl fermions in quantum transport measurements in an epitaxial ferromagnetic oxide SrRuO3.
Collapse
|