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9 results on '"Dashwood, Cameron D."'

1. Strong quantum fluctuations due to competition between magnetic phases in a pyrochlore iridate

Author

Jacobsen, Henrik, Dashwood, Cameron D., Lhotel, Elsa, Khalyavin, Dmitry, Manuel, Pascal, Stewart, Ross, Prabhakaran, Dharmalingam, McMorrow, Desmond F., and Boothroyd, Andrew. T.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

We report neutron diffraction measurements of the magnetic structures in two pyrochlore iridates, Yb2Ir2O7 and Lu2Ir2O7. Both samples exhibit the all-in-all-out magnetic structure on the Ir4+ sites below TN~ 150,K, with a low temperature moment of around 0.45 muB/Ir. Below 2\,K, the Yb moments in Yb2Ir2O7 begin to order ferromagnetically. However, even at 40 mK the ordered moment is only 0.57(3)muB/Yb, well below the saturated moment of the ground state doublet of Yb3+ (1.9 muB/Yb), deduced from magnetization measurements and from a refined model of the crystal field environment, and also significantly smaller than the ordered moment of Yb in Yb2Ti2O7 (0.9 muB/Yb). A mean-field analysis shows that the reduced moment on Yb is a consequence of enhanced phase competition caused by coupling to the all-in-all-out magnetic order on the Ir sublattice., Comment: 14 pages, 10 figures, resubmitted to PRB

Published
2019
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2. Laser-induced transient magnons in Sr₃Ir₂O₇ throughout the Brillouin zone

Author

Mazzone, Daniel G., Meyers, Derek, Cao, Yue, Vale, James G., Dashwood, Cameron D., Shi, Youguo, James, Andrew J. A., Robinson, Neil J., Lin, Jiaqi, Thampy, Vivek, Tanaka, Yoshikazu, Johnson, Allan S., Miao, Hu, Wang, Ruitang, Assefa, Tadesse A., Kim, Jungho, Casa, Diego, Mankowsky, Roman, Zhu, Diling, Alonso-Mori, Roberto, Song, Sanghoon, Yavas, Hasan, Katayama, Tetsuo, Yabashi, Makina, Kubota, Yuya, Owada, Shigeki, Liu, Jian, Yang, Junji, Konik, Robert M., Robinson, Ian K., Hill, John P., McMorrow, Desmond F., Först, Michael, Wall, Simon, Liu, Xuerong, and Dean, Mark P. M.

Published
2021

3. Laser-induced transient magnons in Sr 3 Ir 2 O 7 throughout the Brillouin zone

Author

Mazzone, Daniel G., primary, Meyers, Derek, additional, Cao, Yue, additional, Vale, James G., additional, Dashwood, Cameron D., additional, Shi, Youguo, additional, James, Andrew J. A., additional, Robinson, Neil J., additional, Lin, Jiaqi, additional, Thampy, Vivek, additional, Tanaka, Yoshikazu, additional, Johnson, Allan S., additional, Miao, Hu, additional, Wang, Ruitang, additional, Assefa, Tadesse A., additional, Kim, Jungho, additional, Casa, Diego, additional, Mankowsky, Roman, additional, Zhu, Diling, additional, Alonso-Mori, Roberto, additional, Song, Sanghoon, additional, Yavas, Hasan, additional, Katayama, Tetsuo, additional, Yabashi, Makina, additional, Kubota, Yuya, additional, Owada, Shigeki, additional, Liu, Jian, additional, Yang, Junji, additional, Konik, Robert M., additional, Robinson, Ian K., additional, Hill, John P., additional, McMorrow, Desmond F., additional, Först, Michael, additional, Wall, Simon, additional, Liu, Xuerong, additional, and Dean, Mark P. M., additional

Published
2021
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6. Laser-induced transient magnons in Sr3Ir2O7 throughout the Brillouin zone.

Author

Mazzone, Daniel G., Meyers, Derek, Yue Cao, Vale, James G., Dashwood, Cameron D., Youguo Shi, James, Andrew J. A., Robinson, Neil J., Jiaqi Lin, Thampy, Vivek, Yoshikazu Tanaka, Johnson, Allan S., Hu Miao, Ruitang Wang, Assefa, Tadesse A., Jungho Kim, Casa, Diego, Mankowsky, Roman, Zhu, Diling, and Alonso-Mori, Roberto

Subjects
BRILLOUIN zones, MAGNONS, X-ray scattering, INELASTIC scattering, PHENOMENOLOGICAL theory (Physics)
Abstract

Although ultrafast manipulation of magnetism holds great promise for new physical phenomena and applications, targeting specific states is held back by our limited understanding of how magnetic correlations evolve on ultrafast timescales. Using ultrafast resonant inelastic X-ray scattering we demonstrate that femtosecond laser pulses can excite transient magnons at large wavevectors in gapped antiferromagnets and that they persist for several picoseconds, which is opposite to what is observed in nearly gapless magnets. Our work suggests that materials with isotropic magnetic interactions are preferred to achieve rapid manipulation of magnetism. [ABSTRACT FROM AUTHOR]

Published
2021
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7. Formation of Long-Lived Color Centers for Broadband Visible Light Emission in Low-Dimensional Layered Perovskites

Author

Booker, Edward P, Thomas, Tudor H, Quarti, Claudio, Stanton, Michael R, Dashwood, Cameron D, Gillett, Alexander J, Richter, Johannes M, Pearson, Andrew J, Davis, Nathaniel JLK, Sirringhaus, Henning, Price, Michael B, Greenham, Neil C, Beljonne, David, Dutton, Siân E, Deschler, Felix, Booker, Edward P [0000-0001-8155-8206], Quarti, Claudio [0000-0002-5488-1216], Greenham, Neil C [0000-0002-2155-2432], and Apollo - University of Cambridge Repository

Subjects
0306 Physical Chemistry (incl. Structural)
Abstract

We investigate the origin of the broadband visible emission in layered hybrid lead-halide perovskites and its connection with structural and photophysical properties. We study ⟨001⟩ oriented thin films of hexylammonium (HA) lead iodide, (C6H16N)2PbI4, and dodecylammonium (DA) lead iodide, (C12H28N)2PbI4, by combining first-principles simulations with time-resolved photoluminescence, steady-state absorption and X-ray diffraction measurements on cooling from 300 to 4 K. Ultrafast transient absorption and photoluminescence measurements are used to track the formation and recombination of emissive states. In addition to the excitonic photoluminescence near the absorption edge, we find a red-shifted, broadband (full-width at half-maximum of about 0.4 eV), emission band below 200 K, similar to emission from ⟨110⟩ oriented bromide 2D perovskites at room temperature. The lifetime of this sub-band-gap emission exceeds that of the excitonic transition by orders of magnitude. We use X-ray diffraction measurements to study the changes in crystal lattice with temperature. We report changes in the octahedral tilt and lattice spacing in both materials, together with a phase change around 200 K in DA2PbI4. DFT simulations of the HA2PbI4 crystal structure indicate that the low-energy emission is due to interstitial iodide and related Frenkel defects. Our results demonstrate that white-light emission is not limited to ⟨110⟩ oriented bromide 2D perovskites but a general property of this class of system, and highlight the importance of defect control for the formation of low-energy emissive sites, which can provide a pathway to design tailored white-light emitters.

Published
2018
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8. Formation of Long-Lived Color Centers for Broadband Visible Light Emission in Low-Dimensional Layered Perovskites

Author

Booker, Edward P., Thomas, Tudor H., Quarti, Claudio, Stanton, Michael R., Dashwood, Cameron D., Gillett, Alexander J., Richter, Johannes M., Pearson, Andrew J., Davis, Nathaniel J. L. K., Sirringhaus, Henning, Price, Michael B., Greenham, Neil C., Beljonne, David, Dutton, Siân E., and Deschler, Felix

Abstract

We investigate the origin of the broadband visible emission in layered hybrid lead-halide perovskites and its connection with structural and photophysical properties. We study ⟨001⟩ oriented thin films of hexylammonium (HA) lead iodide, (C6H16N)2PbI4, and dodecylammonium (DA) lead iodide, (C12H28N)2PbI4, by combining first-principles simulations with time-resolved photoluminescence, steady-state absorption and X-ray diffraction measurements on cooling from 300 to 4 K. Ultrafast transient absorption and photoluminescence measurements are used to track the formation and recombination of emissive states. In addition to the excitonic photoluminescence near the absorption edge, we find a red-shifted, broadband (full-width at half-maximum of about 0.4 eV), emission band below 200 K, similar to emission from ⟨110⟩ oriented bromide 2D perovskites at room temperature. The lifetime of this sub-band-gap emission exceeds that of the excitonic transition by orders of magnitude. We use X-ray diffraction measurements to study the changes in crystal lattice with temperature. We report changes in the octahedral tilt and lattice spacing in both materials, together with a phase change around 200 K in DA2PbI4. DFT simulations of the HA2PbI4crystal structure indicate that the low-energy emission is due to interstitial iodide and related Frenkel defects. Our results demonstrate that white-light emission is not limited to ⟨110⟩ oriented bromide 2D perovskites but a general property of this class of system, and highlight the importance of defect control for the formation of low-energy emissive sites, which can provide a pathway to design tailored white-light emitters.

Published
2024
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9. Formation of Long-Lived Color Centers for Broadband Visible Light Emission in Low-Dimensional Layered Perovskites

Author

Booker, Edward P., primary, Thomas, Tudor H., additional, Quarti, Claudio, additional, Stanton, Michael R., additional, Dashwood, Cameron D., additional, Gillett, Alexander J., additional, Richter, Johannes M., additional, Pearson, Andrew J., additional, Davis, Nathaniel J. L. K., additional, Sirringhaus, Henning, additional, Price, Michael B., additional, Greenham, Neil C., additional, Beljonne, David, additional, Dutton, Siân E., additional, and Deschler, Felix, additional

Published
2017
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