| 1. |
- Forslund, Ola Kenji, et al.
(författare)
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Magnetic phase diagram of K2Cr8O16 clarified by high-pressure muon spin spectroscopy
- 2019
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The K2Cr8O16 compound belongs to a series of quasi-1D compounds with intriguing magnetic properties that are stabilized through a high-pressure synthesis technique. In this study, a muon spin rotation, relaxation and resonance (mu+SR) technique is used to investigate the pressure dependent magnetic properties up to 25 kbar. mu+SR allows for measurements in true zero applied field and hereby access the true intrinsic material properties. As a result, a refined temperature/pressure phase diagram is presented revealing a novel low temperature/high pressure (p(C1) = 21 kbar) transition from a ferromagnetic insulating to a high-pressure antiferromagnetic insulator. Finally, the current study also indicates the possible presence of a quantum critical point at p(C2) similar to 33 kbar where the magnetic order in K2Cr8O16 is expected to be fully suppressed even at T = 0 K.
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| 2. |
- Forslund, Ola Kenji, 1990, et al.
(författare)
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Pressure driven magnetic order in Sr 1 - x Ca x Co 2 P 2
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic phase diagram of Sr1-xCaxCo2P2 as a function of hydrostatic pressure and temperature is investigated by means of high pressure muon spin rotation, relaxation and resonance (μ+SR). The weak pressure dependence for the x≠ 1 compounds suggests that the rich phase diagram of Sr1-xCaxCo2P2 as a function of x at ambient pressure may not solely be attributed to chemical pressure effects. The x= 1 compound on the other hand reveals a high pressure dependence, where the long range magnetic order is fully suppressed at pc 2≈ 9.8 kbar, which seem to be a first order transition. In addition, an intermediate phase consisting of magnetic domains is formed above pc 1≈ 8 kbar where they co-exist with a magnetically disordered state. These domains are likely to be ferromagnetic islands (FMI) and consist of an high- (FMI-1) and low-temperature (FMI-2) region, respectively, separated by a phase boundary at Ti≈ 20 K. This kind of co-existence is unusual and is originating from a coupling between lattice and magnetic degrees of freedoms.
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| 3. |
- Forslund, Ola Kenji, et al.
(författare)
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Pressure driven magnetic order in Sr1-xCaxCo2P2
- 2022
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic phase diagram of Sr1-xCaxCo2P2 as a function of hydrostatic pressure and temperature is investigated by means of high pressure muon spin rotation, relaxation and resonance (mu+SR). The weak pressure dependence for the x not equal 1- compounds suggests that the rich phase diagram of Sr1-xCaxCo2P2 as a function of x at ambient pressure may not solely be attributed to chemical pressure effects. The x = 1 compound on the other hand reveals a high pressure dependence, where the long range magnetic order is fully suppressed at p(c2) approximate to 9.8 kbar, which seem to be a first order transition. In addition, an intermediate phase consisting of magnetic domains is formed above p(c1) approximate to 8 kbar where they co-exist with a magnetically disordered state. These domains are likely to be ferromagnetic islands (FMI) and consist of an high- (FMI-(1)) and low-temperature (FMI-(2)) region, respectively, separated by a phase boundary at T-i approximate to 20 K. This kind of co-existence is unusual and is originating from a coupling between lattice and magnetic degrees of freedoms.
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| 4. |
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| 5. |
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| 6. |
- Forslund, Ola Kenji, et al.
(författare)
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μ+SR Study of K2Cr8O16 Under Hydrostatic Pressure
- 2018
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Ingår i: Journal of the Physical Society of Japan. - : Physical Society of Japan. - 0031-9015 .- 1347-4073.
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the magnetic ground state of the hollandite type material K2Cr8O16 was tuned by externally applied pressure and investigated using µ+SR method in Zero-field (ZF) and weak-transversefield (wTF) configurations. As a result, the obtained magnetic transition temperature for the measuredpressures differs notably from magnetization measurements. Moreover, both wTF and ZF data reveala transition between two different magnetically ordered states at low temperatures for higher pressures. Further theoretical and experimental studies are currently being planned in order to elucidatethe detailed nature of the magnetically ordered phase.
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| 7. |
- Ge, Yuqing, 1996, et al.
(författare)
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Confirming the high pressure phase diagram of the Shastry-Sutherland model
- 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
- A Muon Spin Rotation (μ + SR) study was conducted to investigate the magnetic properties of SrCu2(BO3)2 (SCBO) as a function of temperature/pressure. Measurements in zero field and transverse field confirm the absence of long range magnetic order at high pressures and low temperatures. These measurements suggest changes in the Cu spin fluctuations characteristics above 21 kbar, consistent with the formation of a plaquette phase as previously suggested by inelastic neutron scattering measurements. SCBO is the only known realisation of the Shatry-Sutherland model, thus the ground state mediating the dimer and antiferromagnetic phase is likekly to be a plaquette state.
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| 8. |
- Khasanov, Rustem, et al.
(författare)
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Superconducting nature of the Bi-II phase of elemental bismuth
- 2019
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 99:17
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Tidskriftsartikel (refereegranskat)abstract
- The superconductivity in the Bi-II phase of elemental bismuth (transition temperature T-c similar or equal to 3.92 K at pressure p similar or equal to 2.80 GPa) was studied experimentally by means of the muon-spin rotation as well as theoretically by using the Eliashberg theory in combination with density functional theory calculations. Experiments reveal that Bi-II is a type-I superconductor with a zero temperature value of the thermodynamic critical field B-c(0) similar or equal to 31.97 mT. The Eliashberg theory approach provides a good agreement with the experimental T-c and the temperature evolution of B-c . The estimated value for the retardation (coupling) parameter k(B)T(c)/omega(In) approximate to 0.07 (omega(In) is the logarithmically averaged phonon frequency) suggests that Bi-II is an intermediately coupled superconductor.
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| 9. |
- Khasanov, Rustem, et al.
(författare)
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Superconductivity of Bi-III phase of elemental bismuth : Insights from muon-spin rotation and density functional theory
- 2018
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 98:14
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Tidskriftsartikel (refereegranskat)abstract
- Using muon-spin rotation the pressure-induced superconductivity in the Bi-III phase of elemental bismuth (transition temperature T-c similar or equal to 7.05 K) was investigated. A Ginzburg-Landau parameter kappa = lambda/xi = 30(6) (lambda is the magnetic penetration depth, xi is the coherence length) was estimated, which turns out to be the highest among known single element superconductors. The temperature dependence of the superconducting energy gap [Delta(T)] reconstructed from lambda(-2)(T) deviates from the weakly coupled BCS prediction. The coupling strength 2 Delta/k(B)T
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| 10. |
- Miniotaite, Ugne, et al.
(författare)
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Magnetic Properties of Multifunctional 7 LiFePO 4 under Hydrostatic Pressure
- 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
- LiFePO4 (LFPO) is an archetypical and well-known cathode material for rechargeable Li-ion batteries. However, its quasi-one-dimensional (Q1D) structure along with the Fe ions, LFPO also displays interesting low-temperature magnetic properties. Our team has previously utilized the muon spin rotation (μ +SR) technique to investigate both magnetic spin order as well as Li-ion diffusion in LFPO. In this initial study we extend our investigation and make use of high-pressure μ +SR to investigate effects on the low-T magnetic order. Contrary to theoretical predictions we find that the magnetic ordering temperature as well as the ordered magnetic moment increase at high pressure (compressive strain).
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