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Magnetoluminescence from trion and biexciton in type-II quantum dot.

Okuyama R, Eto M, Hyuga H - Nanoscale Res Lett (2011)

Bottom Line: Since the relative motion of electrons are frozen, the Wigner molecule behaves as a composite particle whose mass and charges are twice those of an electron.As a result, the period of AB oscillation for trion and biexciton becomes h/2e as a function of magnetic flux penetrating the ring.We find that the magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by h/2e.PACS: 71.35.Ji, 73.21.-b, 73.21.La, 78.67.Hc.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. rokuyama@rk.phys.keio.ac.jp.

ABSTRACT
We theoretically investigate optical Aharonov-Bohm (AB) effects on trion and biexciton in the type-II semiconductor quantum dots, in which holes are localized near the center of the dot, and electrons are confined in a ring structure formed around the dot. Many-particle states are calculated numerically by the exact diagonalization method. Two electrons in trion and biexciton are strongly correlated to each other, forming a Wigner molecule. Since the relative motion of electrons are frozen, the Wigner molecule behaves as a composite particle whose mass and charges are twice those of an electron. As a result, the period of AB oscillation for trion and biexciton becomes h/2e as a function of magnetic flux penetrating the ring. We find that the magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by h/2e.PACS: 71.35.Ji, 73.21.-b, 73.21.La, 78.67.Hc.

No MeSH data available.


Low-lying energies for two electrons in the type-II quantum dot, as a function of the magnetic flux Φ. Solid and dash lines indicate spin-singlet and triplet, respectively. The ratio of the dot radius R to the effective Bohr radius aB = 4πϵħ2/mee2 is (a) 0.01, (b) 0.1, (c) 1, and (d) 10. The ground-state energy oscillates by the period of h/2e for R/aB ≳ 1.
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Figure 2: Low-lying energies for two electrons in the type-II quantum dot, as a function of the magnetic flux Φ. Solid and dash lines indicate spin-singlet and triplet, respectively. The ratio of the dot radius R to the effective Bohr radius aB = 4πϵħ2/mee2 is (a) 0.01, (b) 0.1, (c) 1, and (d) 10. The ground-state energy oscillates by the period of h/2e for R/aB ≳ 1.

Mentions: In order to elucidate the relation between the electron-electron interaction and the fractional period of AB oscillation, we examine many-body states for two electrons with changing R/aB. Figure 2 shows low-lying energies with (a) R = aB = 0.01, (b) 0.1, (c) 1, and (d) 10. Without the Coulomb interaction, two electrons occupy the lowest orbital shown in Figure 1a in the ground state. Consequently, the total angular momentum is always even, and the total spin is a singlet. As the strength of the Coulomb interaction increases with R/aB, the exchange interaction lowers energies for spin-triplet states compared to singlet states. For R/aB ≳ 1, singlet and triplet states alternatively appear as Φ increases by about h/2e. Hence, the ground-state energy oscillates with Φ by the period of h/2e. Note that the period of AB oscillation in the case of R/aB = 10 is slightly shorter than that of R/aB = 1. This is because the Coulomb repulsion between electrons tends to increase the expectation value of the electron radius.


Magnetoluminescence from trion and biexciton in type-II quantum dot.

Okuyama R, Eto M, Hyuga H - Nanoscale Res Lett (2011)

Low-lying energies for two electrons in the type-II quantum dot, as a function of the magnetic flux Φ. Solid and dash lines indicate spin-singlet and triplet, respectively. The ratio of the dot radius R to the effective Bohr radius aB = 4πϵħ2/mee2 is (a) 0.01, (b) 0.1, (c) 1, and (d) 10. The ground-state energy oscillates by the period of h/2e for R/aB ≳ 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211441&req=5

Figure 2: Low-lying energies for two electrons in the type-II quantum dot, as a function of the magnetic flux Φ. Solid and dash lines indicate spin-singlet and triplet, respectively. The ratio of the dot radius R to the effective Bohr radius aB = 4πϵħ2/mee2 is (a) 0.01, (b) 0.1, (c) 1, and (d) 10. The ground-state energy oscillates by the period of h/2e for R/aB ≳ 1.
Mentions: In order to elucidate the relation between the electron-electron interaction and the fractional period of AB oscillation, we examine many-body states for two electrons with changing R/aB. Figure 2 shows low-lying energies with (a) R = aB = 0.01, (b) 0.1, (c) 1, and (d) 10. Without the Coulomb interaction, two electrons occupy the lowest orbital shown in Figure 1a in the ground state. Consequently, the total angular momentum is always even, and the total spin is a singlet. As the strength of the Coulomb interaction increases with R/aB, the exchange interaction lowers energies for spin-triplet states compared to singlet states. For R/aB ≳ 1, singlet and triplet states alternatively appear as Φ increases by about h/2e. Hence, the ground-state energy oscillates with Φ by the period of h/2e. Note that the period of AB oscillation in the case of R/aB = 10 is slightly shorter than that of R/aB = 1. This is because the Coulomb repulsion between electrons tends to increase the expectation value of the electron radius.

Bottom Line: Since the relative motion of electrons are frozen, the Wigner molecule behaves as a composite particle whose mass and charges are twice those of an electron.As a result, the period of AB oscillation for trion and biexciton becomes h/2e as a function of magnetic flux penetrating the ring.We find that the magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by h/2e.PACS: 71.35.Ji, 73.21.-b, 73.21.La, 78.67.Hc.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. rokuyama@rk.phys.keio.ac.jp.

ABSTRACT
We theoretically investigate optical Aharonov-Bohm (AB) effects on trion and biexciton in the type-II semiconductor quantum dots, in which holes are localized near the center of the dot, and electrons are confined in a ring structure formed around the dot. Many-particle states are calculated numerically by the exact diagonalization method. Two electrons in trion and biexciton are strongly correlated to each other, forming a Wigner molecule. Since the relative motion of electrons are frozen, the Wigner molecule behaves as a composite particle whose mass and charges are twice those of an electron. As a result, the period of AB oscillation for trion and biexciton becomes h/2e as a function of magnetic flux penetrating the ring. We find that the magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by h/2e.PACS: 71.35.Ji, 73.21.-b, 73.21.La, 78.67.Hc.

No MeSH data available.