Electron Spin Resonance of Proton-Irradiated Graphite

Lee, Kyu Won; Lee, Cheol Eui

doi:10.1103/physrevlett.97.137206

Cited by 63 publications

(39 citation statements)

References 28 publications

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“…For an ion fluence of 10/nm 2 [ Fig. 4(b)], we find an additional narrow ESR line corresponding to g 2.002 as expected for graphene vacancies [18]. The apparent line width can be determined from a fit, which is optimal, if a mixture of a Gaussian and a Lorentzian of similar strength are used.…”

Section: Esr Results On Graphenementioning

confidence: 99%

Preferential antiferromagnetic coupling of vacancies in graphene onSiO2: Electron spin resonance and scanning tunneling spectroscopy

et al. 2014

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Monolayer graphene grown by chemical vapor deposition and transferred to SiO2 is used to introduce vacancies by Ar + ion bombardment at a kinetic energy of 50 eV. The density of defects visible in scanning tunneling microscopy (STM) is considerably lower than the ion fluence implying that most of the defects are single vacancies as expected from the low ion energy. The vacancies are characterized by scanning tunneling spectroscopy (STS) on graphene and HOPG. A peak close to the Dirac point is found within the local density of states of the vacancies similar the the peak found previously for vacancies on HOPG. The peak persists after air exposure up to 180 min, such that electron spin resonance (ESR) at 9.6 GHz can probe the vacancies exhibiting such a peak. After an ion flux of 10/nm 2 , we find an ESR signal corresponding to a g-factor of 2.001-2.003 and a spin density of 1-2 spins/nm 2 . The peak width is as small as 0.17 mT indicating exchange narrowing. Consistently, the temperature dependent measurements reveal antiferromagnetic correlations with a Curie-Weiss temperature of -10 K. Thus, the vacancies preferentially couple antiferromagnetically ruling out a ferromagnetic graphene monolayer at ion induced spin densities of 1 − 2/nm 2 .

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Section: Esr Results On Graphenementioning

confidence: 99%

Preferential antiferromagnetic coupling of vacancies in graphene onSiO2: Electron spin resonance and scanning tunneling spectroscopy

et al. 2014

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“…Actually, SQUID measurements indicate that HOPG samples irradiated with Ar 11+ at the fluence in the order of 10 14 ions/cm 2 have greater magnetizations than samples irradiated with monovalent ions at the fluence of 1.875 × 10 17 ions/cm 2 as in Ref. [9]. It is necessary to perform measurements over various charge state and fluence in order to reveal the effect of potential energy on magnetic modification of materials by HCI injection in detail.…”

Section: Resultsmentioning

confidence: 94%

“…Highly oriented pyrolytic graphite (HOPG) samples irradiated with monovalent ions have been studied by electron spin resonance (ESR) and superconducting quantum interferometer device (SQUID) as a study of magnetism of HOPG irradiated with ions [6][7][8][9]. When a proton was injected, resonance peak due to the ion injection was observed at the fluence of 10 16 cm −2 .…”

Section: +mentioning

confidence: 99%

ESR Measurements of HOPG Irradiated with Highly Charged Ions

Nishida

Betsumiya

Sakurai

et al. 2018

e-J. Surf. Sci. Nanotech.

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Electron spin resonance (ESR) measurements were performed on highly oriented pyrolytic graphite (HOPG) samples irradiated with highly charged ions (HCIs). The interaction between a HCI and surfaces results in emission of photons in the range of visible to X-ray, hundreds of secondary electrons, sputtering of secondary ions and modification of surface structure in nanometer scale. In the present experiments, HCIs were produced by electron beam ion source (EBIS) and Ar 8+ and Ar 14+ were used for the irradiation. ESR measurement provides information on unpaired electrons of the sample. We investigated the dependence of defect formation on charge state and fluence of incident HCIs using ESR. The L1 line appeared in HOPG samples irradiated with HCIs at the low temperature region, and the intensity became larger at higher charge state and higher fluence.

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“…As established by magnetometry and ESR studies of the vacancy moments in neutron-and proton-irradiated graphite, respectively, the magnetic monovancy states are associated with a spin moment S = 1/2, a magnetic moment of 1 µ B and an electronic g-factor of about 2 [40,53]. Correspondingly, the Zeeman energy in an applied field of B = 7.1 Tesla is gµ B m z B = 0.41 meV (or 4.76 K), which exactly equals the observed excitation gap.…”

Section: Resultsmentioning

confidence: 99%

Monovacancy paramagnetism in neutron-irradiated graphite probed by¹³C NMR

Zhang

Dmytriieva

et al. 2017

J. Phys.: Condens. Matter

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Abstract. We report on the magnetic properties of monovacancy defects in neutron-irradiated graphite, probed by 13 C nuclear magnetic resonance spectroscopy. The bulk paramagnetism of the defect moments is revealed by the temperature dependence of the NMR frequency shift and spectral linewidth, both of which follow a Curie behavior, in agreement with measurements of the macroscopic magnetization. Compared to pristine graphite, the fluctuating hyperfine fields generated by the defect moments lead to an enhancement of the 13 C nuclear spin-lattice relaxation rate 1/T 1 by about two orders of magnitude. With an applied magnetic field of 7.1 T, the temperature dependence of 1/T 1 below about 10 K can well be described by a thermally activated form, 1/T 1 ∝ exp(−∆/k B T ), yielding a singular Zeeman energy of (0.41 ± 0.01) meV, in excellent agreement with the sole presence of polarized, non-interacting defect moments.

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Electron Spin Resonance of Proton-Irradiated Graphite

Cited by 63 publications

References 28 publications

Preferential antiferromagnetic coupling of vacancies in graphene onSiO2: Electron spin resonance and scanning tunneling spectroscopy

Preferential antiferromagnetic coupling of vacancies in graphene onSiO2: Electron spin resonance and scanning tunneling spectroscopy

ESR Measurements of HOPG Irradiated with Highly Charged Ions

Monovacancy paramagnetism in neutron-irradiated graphite probed by¹³C NMR

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Electron Spin Resonance of Proton-Irradiated Graphite

Cited by 63 publications

References 28 publications

Preferential antiferromagnetic coupling of vacancies in graphene onSiO2: Electron spin resonance and scanning tunneling spectroscopy

Preferential antiferromagnetic coupling of vacancies in graphene onSiO2: Electron spin resonance and scanning tunneling spectroscopy

ESR Measurements of HOPG Irradiated with Highly Charged Ions

Monovacancy paramagnetism in neutron-irradiated graphite probed by13C NMR

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Monovacancy paramagnetism in neutron-irradiated graphite probed by¹³C NMR