| 51. |
- Papadopoulos, Konstantinos, 1989, et al.
(författare)
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Influence of the magnetic sublattices in the double perovskite LaCaNiReO6
- 2022
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9969 .- 2469-9950. ; 106:21
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Tidskriftsartikel (refereegranskat)abstract
- The magnetism of double perovskites is a complex phenomenon, determined from intra- or interatomic magnetic moment interactions, and strongly influenced by geometry. We take advantage of the complementary length and timescales of the muon spin rotation, relaxation, and resonance (μ+SR) microscopic technique and bulk ac/dc magnetic susceptibility measurements to study the magnetic phases of the LaCaNiReO6 double perovskite. As a result, we are able to discern and report ferrimagnetic ordering below TC=102K and the formation of different magnetic domains above TC. Between TC270K. An evolution of the interaction between Ni and Re magnetic sublattices, in this geometrically frustrated fcc perovskite structure, is revealed as a function of temperature through the critical behavior and thermal evolution of microscopic and macroscopic physical quantities.
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| 52. |
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| 53. |
- Sugiyama, Jun, et al.
(författare)
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Lithium diffusion in LiMnPO4 detected with mu +/- SR
- 2020
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Ingår i: Physical Review Research. - : American Physical Society (APS). - 2643-1564. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- Positive- and negative-muon spin rotation and relaxation (mu(+/-) SR) was first used to investigate fluctuations of nuclear magnetic fields in an olivine-type battery material, LiMnPO4, in order to clarify the diffusive species, namely, to distinguish between a mu(+) hopping among interstitial sites and Li+ ions diffusing in the LiMnPO4 lattice. Muon diffusion can only occur in mu+SR, because the implanted mu(-) forms a stable muonic atom at the lattice site, and therefore any change in linewidth measured with mu-SR must be due to Li+ diffusion. Since the two measurements exhibit a similar increase in the field fluctuation rate with temperature above 100 K, it is confirmed that Li+ ions are in fact diffusing. The diffusion coefficient of Li+ at 300 K and its activation energy were estimated to be 1.4(3) x 10(-10) cm(2)/s and 0.19(3) eV, respectively. Such combined mu(SR)-S-+/- measurements are thus shown to be a suitable tool for detecting ion diffusion in solid-state energy materials.
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| 54. |
- Sugiyama, Jun, et al.
(författare)
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Magnetic phase boundary of BaVS3 clarified with high-pressure mu+SR
- 2020
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9969 .- 2469-9950. ; 101:17
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic nature of the quasi-one-dimensional BaVS3 has been studied as a function of temperature down to 0.25 K and pressure up to 1.97 GPa on a powder sample using the positive muon spin rotation and relaxation (mu(+) SR) technique. At ambient pressure, BaVS3 enters an incommensurate antiferromagnetic ordered state below the Neel temperature (T-N)31 K. T-N is almost constant as the pressure (p) increases from ambient pressure to 1.4 GPa, then T-N decreases rapidly for p > 1.4 GPa, and finally disappears at p similar to 1.8 GPa, above which a metallic phase is stabilized. Hence, T-N is found to be equivalent to the pressure-induced metal-insulator transition temperature (T-MI) at p > 1.4 GPa.
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| 55. |
- Sugiyama, Jun, et al.
(författare)
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Negative muon spin rotation and relaxation on superconducting MgB2
- 2023
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Ingår i: Proceedings 15th International Conference on Muon Spin Rotation, Relaxation and Resonance (SR). - : IOP Publishing.
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Konferensbidrag (refereegranskat)abstract
- The internal nuclear magnetic field in a superconducting MgB2 powder sample was studied with a mu-SR technique. Although the past mu+SR study on MgB2 reported the appearance of a dynamic behavior even below T-c due to mu(+) diffusion, mu-SR shows a static behavior in the whole temperature range measured, as expected. The ZF-mu-SR spectra do not suggest any appearance of additional magnetic field below T-c within the experimental accuracy. Considering the small asymmetry of the mu-SR signal, it is a challenge to detect the appearance of an internal magnetic field below Tc caused by the time reversal symmetry breaking.
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| 56. |
- Sugiyama, Jun, et al.
(författare)
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Nuclear magnetic field in Na0.7CoO2 detected with mu-SR
- 2020
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 102:14
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Tidskriftsartikel (refereegranskat)abstract
- The internal magnetic field in a sodium battery compound, i.e., the paramagnet Na0.7CoO2, was investigated with negative muon spin rotation and relaxation (mu-SR), and the result was compared with the results previously obtained with mu+SR. The majority of implanted mu(-) is captured on an oxygen nucleus, while mu(+) locates an interstitial site. Therefore, a mu(+/-) SR work provides information on the internal magnetic field, which is formed by nuclear magnetic moments of Na-23 and Co-59, from the two different viewpoints. Besides a slight decrease in the field distribution width (Delta) around 300 K, the nuclear magnetic field detected with mu- SR was found to be almost static and temperature independent up to 400 K, even though Na ions are known to start to diffuse above 290 K based on mu(+) SR, Na-NMR, neutron scattering, and electrochemical measurements. Such a discrepancy is caused by the fact that the Na contribution to Delta is only about 3% at the O site whereas it is about 13% at the interstitial site, where the mu(+) is presumably located.
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| 57. |
- Sugiyama, Jun, et al.
(författare)
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Pressure dependence of ferromagnetic phase boundary in BaVSe3 studied with high-pressure μ+SR
- 2021
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9969 .- 2469-9950. ; 103:10
-
Tidskriftsartikel (refereegranskat)abstract
- The magnetic nature of a quasi-one-dimensional compound, BaVSe3, has been investigated with positive muon spin rotation and relaxation (μ+SR) measurements at ambient and high pressures. At ambient pressure, the μ+SR spectrum recorded under zero external magnetic field exhibited a clear oscillation below the Curie temperature (TC∼41K) due to the formation of quasistatic ferromagnetic order. The oscillation consisted of two different muon spin precession signals, indicating the presence of two magnetically different muon sites in the lattice. However, the two precession frequencies, which correspond to the internal magnetic fields at the two muon sites, could not be adequately explained with relatively simple ferromagnetic structures using the muon sites predicted by density functional theory calculations. The detailed analysis of the internal magnetic field suggested that the V moments align ferromagnetically along the c axis but slightly canted toward the a axis by 28 that is coupled antiferromagnetically. The ordered V moment (MV) is estimated as (0.59, 0, 1.11) μB. As pressure increased from ambient pressure, TC was found to decrease slightly up to about 1.5 GPa, at which point TC started to increase rapidly with the further increase of the pressure. Based on a strong ferromagnetic interaction along the c axis, the high-pressure μ+SR result revealed that there are two magnetic interactions in the ab plane; one is an antiferromagnetic interaction that is enhanced with pressure, mainly at pressures below 1.5 GPa, while the other is a ferromagnetic interaction that becomes predominant at pressures above 1.5 GPa.
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| 58. |
- Sugiyama, Jun, et al.
(författare)
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Search for a space charge layer in thin film battery materials with low-energy muons
- 2023
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 2462:1
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Konferensbidrag (refereegranskat)abstract
- In an all solid state Li-ion battery, it is crucial to reduce ionic resistivity at the interface between the electrode and the electrolyte in order to enhance Li+ mobility across the interface. Recent first principles calculations predict the presence of a space-charge layer (SCL) at the interface due to the difference in the Li+ chemical potential at the interface between two different materials, as in the metal-semiconductor junction in electronic devices. However, the presence of SCL has never been experimentally observed. Our first attempt in a fresh multilayer sample, Cu(10 nm)/Li3PO4(50 nm)/LiCoO2(100 nm) on a sapphire substrate, with low-energy μ +SR (LE μ +SR) revealed a gradual change in the nuclear magnetic field distribution width as a function of implantation depth even across the interface between Li3PO4 and LiCoO2. This implies that the change in the field distribution width at SCL of the sample is too small to be detected by LE μ +SR.
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| 59. |
- Witteveen, Catherine, et al.
(författare)
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Synthesis and anisotropic magnetic properties of LiCrTe2 single crystals with a triangular-lattice antiferromagnetic structure
- 2023
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Ingår i: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- We report on the synthesis of LiCrTe2 single crystals and on their anisotropic magnetic properties. We have obtained these single crystals by employing a Te/Li-flux synthesis method. We find LiCrTe2 to crystallize in a TlCdS2 -type structure with cell parameters of a = 3.9512(5) angstrom and c = 6.6196(7) angstrom at T = 175 K. The content of lithium in these crystals was determined to be neary stoichiometric by means of neutron diffraction. We find a pronounced magnetic transition at T-N(ab) = 144 K and T-N
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