Colloquium Talk: Dr. Que Huong Nguyen – 12/5/2018!
Science Building Room 276, 2:00pm – 3:00pm
The next Colloquium talk will be Dr. Que Huong Nguyen, Professor of Physics Department, talking about “Emission in Maganese -Doped Semiconductor Nanocrystals”.
With recent development of nanotechnology such as colloidal synthesis and molecular -beam epitaxy, magnetic ion-doped quantum dots (QDs) become a great interest and have been studied intensively. Well known as an activator for photoluminescence (PL) and electroluminescence, the ion Mn2+ has been among the first magnetic ion to be doped into a semiconductor nanocrystals (NCs)Up to date, considerable interest has been attracted in the Mn-doped semiconductor NCs. The Mn-Doped QD can not only maintain nearly all the intrinsic advantages of QDs, but also bring the additional merits such as larger Stokes shifts, enhanced thermal and chemical stabilities, as well as longer excited state lifetimes.
We theoretically investigate the magneto- PL of Mn2+doped semiconductor core-shell colloidal QD to explain the experiment results from a recent magneto-PL study (1,2) of strongly confined diluted magnetic semiconductor (DMS) in Mn2+-doped ZnSe/CdSe core-shell colloidal NCs. Unlike the cases in bulks or in other conventional DMS materials, the yellow emission characterized for in Mn2+ which is associated with the d-d internal transition 4T1- 6A1, was reported not suppressed in an applied //z magnetic field and circularly polarized as usual and instead, developed a circular polarization. More interestingly, Mn2+ PL has been found to have a large splitting between σ+ and σ−components which depends on the applied field. This behaviour has not been found in characteristics of the Mn2+ PL in bulks and other conventional DMS materials and is the result of the strong confinement of the NCs.
Our theory shows that, the reason the yellow Mn2+ PL band in QDs, indifferent to their counterparts in bulks and other low-dimensional systems, is not suppressed under applied magnetic field originates from the dot geometry and properties. The theory of Coulomb exchange interaction of the impurity ions with the confined electrons inside the dot as well the existence of the internal electric field inside the dot show that these two effects might be the reasons of the observed behaviours. The competition and combination between these two effects give different results depending on parameters and conditions.
The talk will be accessible and of interest for all majors!
PHY 350 BioPhysics – Spring 2019
Distinguished Traveling Lecturer – 4/3/2019 and 4/4/2019!
The Marshall University Physics department is proud to announce that they have been awarded the opportunity to host Dr. Luis Orozco (see his website: https://jqi.umd.edu/people/luis-orozco/) as a Distinguished Traveling Lecturer on April 3rd and 4th of 2019. This will be co-sponsored by the American Physical Society and the MU Physics Department. For more information about Dr. Luis Orozco’s visit, please contact Dr. Thomas Wilson (firstname.lastname@example.org) in the Physics Department at Marshall University. This 2-day visit will have both public talks and student student-oriented talks (4 talks in total). All times and locations for this 2-day event have yet to be determine, but will be announced as soon as they become available.
Contact Dr. Sachiko McBride (email@example.com) if you have trouble accessing the Physics Department website or experience errors. Questions about the content can be addressed to Dr. Sean McBride (firstname.lastname@example.org).