In-plane nuclear field formation investigated in single self-assembled quantum dots

Yamamoto, Sho; Matsusaki, Ryosuke; Kaji, R.; Adachi, S.

doi:10.1103/physrevb.97.075309

Cited by 10 publications

(34 citation statements)

References 28 publications

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“…These studies suggest strongly that the nuclear quadrupole interaction (NQI), which is caused from the coupling of nuclear spin and electric‐field gradient induced by the residual strain in SA‐QDs, contributes to the formation of a large in‐plane nuclear field. To date, we have proposed a formation model of the large in‐plane nuclear field by considering the effects of NQI and successfully obtained a qualitative agreement with the observed anomalous Hanle curves . In the model, two effects, the stabilization of NSP along the principal axis of NQI and strongly anisotropic response of nuclear states due to the eigenstate mixing, are included as the effects of NQI.…”

Section: Introductionmentioning

confidence: 73%

“…Obviously, the observed curve is distorted drastically from a normal one. The anomalous broadening indicates the presence of the in‐plane nuclear field

B_{n, x}

which develops with compensating for B x until the critical field B c where the abrupt change in ρ c occurs . The value of B c depends on the sweep direction of B x ;

| B_{normalc} |

with increasing

| B_{x} |

was larger than that with decreasing

| B_{x} |

.…”

Section: Azimuth Angle Dependence Of the Anomalous Hanle Curvementioning

confidence: 97%

“…According to Equation ,

⟨ S_{x} ⟩

is written as

⟨ S_{x} ⟩ = S_{0} \frac{B_{T, z}^{(e)} B_{T, x}^{(e)} + B_{1 / 2} B_{T, y}^{(e)}}{B_{1 / 2}^{2} + {bold-italicB}_{normalT}^{(e)} \cdot {bold-italicB}_{normalT}^{(e)}}

Since only the component of B n along the effective field on nuclei is preserved, the y component of B n ,

B_{n, y}

, is considered to be very small . In this situation where

B_{T, y}^{(e)}

is negligible, the finite

⟨ S_{x} ⟩

calls for a nonzero value of

B_{T, z}^{(e)}

.…”

Section: Azimuth Angle Dependence Of the Anomalous Hanle Curvementioning

confidence: 99%

“…Since

B_{n, z}

originates from the out‐of‐plane component of NSP

⟨ I_{z} ⟩

, the relaxation of

⟨ I_{z} ⟩

due to the nuclear spin precession by B x is an issue for the formation of a large

B_{n, z}

. This can be settled by considering the stabilization of

⟨ I_{z} ⟩

due to the enhanced NQI in SA‐QDs …”

Section: Azimuth Angle Dependence Of the Anomalous Hanle Curvementioning

confidence: 99%

“…Recently, a large nuclear field orthogonal to the photo‐injected electron spin has been reported in the self‐assembled (SA) InAs and InAlAs QDs, which is beyond the scope of a traditional model where a large nuclear field parallel to the injected electron spin was mainly discussed. Such a large in‐plane nuclear field induces a drastic distortion of the electron spin depolarization curve under the transverse magnetic field (i.e., Hanle curve), whereas W‐shaped Hanle curve in a strain‐free

{GaAs/Al}_{0.3} {Ga}_{0.7}

As QD was reproduced reasonably with the traditional model .…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Influence of a Longitudinal Field on the Large In‐Plane Nuclear Field Formation in Single Quantum Dots

Yamamoto

Arakawa

Matsusaki

et al. 2019

Physica Status Solidi (b)

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Experimental studies on the role of nuclear quadrupole interaction (NQI) to the in-plane nuclear field formation are performed in single self-assembled In 0.75 Al 0.25 As= Al 0.3 Ga 0.7 As quantum dots (QDs). In Hanle-effect measurements, the electron depolarization curves deviating far from a standard Lorentzian shape are observed: the curves with anomalously large width and hysteretic behavior at the critical transverse magnetic field. These anomalies indicate the growth of an in-plane nuclear field compensating the applied transverse magnetic field up to %1 T and appear regardless of the excitation helicity. The azimuth angle dependence of the critical field of the hysteretic response reveals that the principal axis of the NQI is almost parallel to the crystal growth axis. This fact suggests that the main origin of the NQI which is related with in-plane nuclearfield formation is not random alloying among In and Al nuclei but residual strain of QDs. Furthermore, a longitudinal magnetic field by a neodymium magnet breaks the excitation-helicity independence of the Hanle curves and the shape of curves becomes very different depending on the helicity. The obtained results are explained well with a simple consideration and indicate that the NQI takes multirole in the formation of in-plane nuclear field.

show abstract

Section: Introductionmentioning

confidence: 73%

“…Obviously, the observed curve is distorted drastically from a normal one. The anomalous broadening indicates the presence of the in‐plane nuclear field

B_{n, x}

which develops with compensating for B x until the critical field B c where the abrupt change in ρ c occurs . The value of B c depends on the sweep direction of B x ;

| B_{normalc} |

with increasing

| B_{x} |

was larger than that with decreasing

| B_{x} |

.…”

Section: Azimuth Angle Dependence Of the Anomalous Hanle Curvementioning

confidence: 97%

“…According to Equation ,

⟨ S_{x} ⟩

is written as

⟨ S_{x} ⟩ = S_{0} \frac{B_{T, z}^{(e)} B_{T, x}^{(e)} + B_{1 / 2} B_{T, y}^{(e)}}{B_{1 / 2}^{2} + {bold-italicB}_{normalT}^{(e)} \cdot {bold-italicB}_{normalT}^{(e)}}

Since only the component of B n along the effective field on nuclei is preserved, the y component of B n ,

B_{n, y}

, is considered to be very small . In this situation where

B_{T, y}^{(e)}

is negligible, the finite

⟨ S_{x} ⟩

calls for a nonzero value of

B_{T, z}^{(e)}

.…”

Section: Azimuth Angle Dependence Of the Anomalous Hanle Curvementioning

confidence: 99%

“…Since

B_{n, z}

originates from the out‐of‐plane component of NSP

⟨ I_{z} ⟩

, the relaxation of

⟨ I_{z} ⟩

due to the nuclear spin precession by B x is an issue for the formation of a large

B_{n, z}

. This can be settled by considering the stabilization of

⟨ I_{z} ⟩

due to the enhanced NQI in SA‐QDs …”

Section: Azimuth Angle Dependence Of the Anomalous Hanle Curvementioning

confidence: 99%

{GaAs/Al}_{0.3} {Ga}_{0.7}

As QD was reproduced reasonably with the traditional model .…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Influence of a Longitudinal Field on the Large In‐Plane Nuclear Field Formation in Single Quantum Dots

Yamamoto

Arakawa

Matsusaki

et al. 2019

Physica Status Solidi (b)

View full text Add to dashboard Cite

show abstract

Anomalous Hanle curves induced by in-plane nuclear field in single self-assembled InAlAs and InAs nanostructures

Yamamoto

Matsusaki

Kaji

et al. 2019

J. Phys.: Conf. Ser.

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We studied the formation mechanism of in-plane nuclear field by anomalous Hanle effect measurements in single self-assembled In0.75Al0.25As/Al0.3Ga0.7As quantum dots and InAs/GaAs quantum rings. The observed anomalous Hanle curves indicated quite large width and hysteretic behavior to the externally applied magnetic field. These anomalies appears in both materials whose electron g factors have opposite sign each other, and cannot be reproduced by a traditional spin dynamics model. In this study, we show that a proposed spin dynamics model can explain the formation of a large in-plane nuclear field regardless of the sign of electron g factor. The model is based on the dynamic nuclear spin polarization mechanism including the effects of nuclear quadrupole interaction.

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Oblique Nuclear Quadrupole Interaction in Self-Assembled Structures Based on Semiconductor Quantum Dots

et al. 2020

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Dynamic nuclear polarization (DNP) is well recognized as being important in spintronics and quantuminformation processing. DNP gives rise to high nuclear spin polarization that not only can prolong electron-spin lifetime by generating an Overhauser field (OHF), but also has fertilized the idea to explore nuclear spin qubits. In strained quantum-dot structures (QDSs), a nuclear spin is coupled to a strain field via its quadrupole moment. It has been shown that such nuclear quadrupole interaction (NQI) can be used to achieve appreciable DNP and hence electron-spin polarization. Here, we uncover magneto-optical anomalies from a series of laterally arranged (In,Ga)As QDSs that arise from the NQI and DNP in these nanostructures. We find that the principal axis of NQI in symmetry-lowered QDSs significantly deviates from the growth direction, resulting in tilting of OHF with an angle exceeding 37°. The resulting transverse component of OHF is probed with respect to the crystallographic orientations and its influence on the DNP and ensemble spin dephasing is analyzed. We show that a high-symmetry electronic confinement potential for excitons does not guarantee a high-symmetry NQI for nuclei within the same nano-object, thereby calling for correlated optimization in the symmetry of the electronic confinement potential and that of the nuclear spin bath. Our results underline the role of oblique NQI in electron-spin decoherence and depolarization, which has so far largely been overlooked. This work thus sheds light on design rules for engineering the electronic and spin landscape of QDSs for better performance of DNP desirable for applications in spintronics and quantum computation.

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In-plane nuclear field formation investigated in single self-assembled quantum dots

Cited by 10 publications

References 28 publications

Influence of a Longitudinal Field on the Large In‐Plane Nuclear Field Formation in Single Quantum Dots

Influence of a Longitudinal Field on the Large In‐Plane Nuclear Field Formation in Single Quantum Dots

Anomalous Hanle curves induced by in-plane nuclear field in single self-assembled InAlAs and InAs nanostructures

Oblique Nuclear Quadrupole Interaction in Self-Assembled Structures Based on Semiconductor Quantum Dots

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