Spin defects in hBN as promising temperature, pressure and magnetic field quantum sensors

Abstract

Spin defects in solid-state materials are strong candidate systems for quantum information technology and sensing applications. Here we explore in details the recently discovered negatively charged boron vacancies (VB−) in hexagonal boron nitride (hBN) and demonstrate their use as atomic scale sensors for temperature, magnetic fields and externally applied pressure. These applications are possible due to the high-spin triplet ground state and bright spin-dependent photoluminescence of the VB−. Specifically, we find that the frequency shift in optically detected magnetic resonance measurements is not only sensitive to static magnetic fields, but also to temperature and pressure changes which we relate to crystal lattice parameters. We show that spin-rich hBN films are potentially applicable as intrinsic sensors in heterostructures made of functionalized 2D materials.

Excited-state spin-resonance spectroscopy of V$_\text{B}^-$ defect centers in hexagonal boron nitride

“…We fit the ESR data with Eq.2 to extract the Hamiltonian parameters. Our measurements agree with previously reported [16,23,1,26] GS splitting parameters D gs = 3.48 ± 0.02 GHz and E gs = 48.0 ± 7.1 MHz, and establish the ES splitting parameters D es = 2.11 ± 0.03 GHz and E es = 74 ± 42 MHz. We also observe that g es ≈ g gs ≈ 2, which indicates that the orbital angular momentum does not play a significant role in the ES spin structure.…”

“…Rapid progress is being made in integrating hBN defects into nano-photonic devices with waveguides [13] and optical cavities [14,44] to achieve high signal-to-noise ratios for sensing applications. We also envision using V − B defects as quantum sensors [16] for magnetization of layered out-of-plane magnets like CrI 3 and CrBr 3 .…”

“…The recent advent of two-dimensional (2D) materials has stimulated the search for spin-active defects that can be integrated into van der Waals heterostructures, enabling a wide array of optoelectronic and nanophotonic devices that take advantage of its optical and spin properties [5,6,7,8,9,10,11,12,13,14]. A spin-active defect in a 2D material is especially promising for nanoscale sensing of interfacial phenomena with high sensitivity due to narrow spin transition linewidths and the ability to position these atomic-scale systems at sub-nanometer distances from the surface of a sample [15,16].…”

Unveiling the Zero-Phonon Line of the Boron Vacancy Center by Cavity Enhanced Emission

“…Negatively charged boron vacancies (V − B ) in hexagonal boron nitride (hBN) are novel quantum emitters that currently attract broad interest due to their spin-dependent optical properties, even at room temperature. [1][2][3][4][5][6] The electronic states of V − B in hBN couple strongly to local vibrational modes, with a Huang-Rhys factor of ∼ 3.5. 1 Combined with singlet and triplet electronic sub-systems that are coupled via spin-orbit interaction and mix via Jahn-Teller effects, this results in a broad and largely featureless emission spectrum that complicates comparison of experimental results with first principles calculations.…”

Spin defects in hexagonal boron nitride for strain sensing on nanopillar arrays

“…[16][17][18] A particular spin defect that garners significant attention is the negatively charged boron vacancy (V B − ). [19][20][21][22][23][24][25][26][27][28][29][30][31] The V B − spin can be initialized, manipulated, and read out optically, with coherence times on the order of several microseconds at room temperature. 17 The V B − defect has a triplet ground state with a zero-field splitting (ZFS) D gs /h of ∼3.46 GHz and a broad emission around 800 nm.…”