Tunable sub-terahertz resonance absorption in high-coercivity magnetodielectric ceramics.

Recently, giant coercivities (20-42 kOe) and sub-terahertz natural ferromagnetic resonance (NFMR) at 100-300 GHz were observed for single-domain M-type hexaferrite particles with high aluminum substitution. Herein, we fabricated dense ceramics of SrCaFeAlO and, for the first time, investigated their magnetostatic and magnetodynamic properties in the temperature range of 5-300 K. It was shown that dense ceramics maintain their high magnetic hardness (a coercivity of 10-20 kOe) and NFMR frequencies of 140-200 GHz durably in the entire temperature range.

Nanoceramics of metastable ε-FeO: effect of sintering on the magnetic properties and sub-terahertz electron resonance.

In this study, we demonstrate the sintering of metastable ε-FeO nanoparticles into nanoceramics containing 98 wt% of the epsilon iron oxide phase and with a specific density of 60%. At room temperature, the ceramics retain a giant coercivity of 20 kOe and a sub-terahertz absorption at 190 GHz inherent in the initial nanoparticles. The sintering leads to an increase in the frequencies of the natural ferromagnetic resonance at 200-300 K and larger coercivities at temperatures below 150 K.

Hard ferrite magnetic insulators revealing giant coercivity and sub-terahertz natural ferromagnetic resonance at 5-300 K.

The temperature behavior of the magnetic properties is crucial for the application of magnetic materials. Recently, giant room temperature coercivities (20-36 kOe) and sub-terahertz natural ferromagnetic resonance (NFMR) frequencies (160-250 GHz) were observed for single-domain M-type hexaferrites with high aluminum substitution. Herein, the temperature dependences of the magnetic properties and natural ferromagnetic resonance are studied at 5-300 K for single-domain SrCaFeAlO ( = 1.

Correction: High-coercivity hexaferrite ceramics featuring sub-terahertz ferromagnetic resonance.

Correction for 'High-coercivity hexaferrite ceramics featuring sub-terahertz ferromagnetic resonance' by Evgeny A. Gorbachev , , 2022, , 1264-1272, DOI: https://doi.org/10.

High-Quality Graphene Using Boudouard Reaction.

Following the game-changing high-pressure CO (HiPco) process that established the first facile route toward large-scale production of single-walled carbon nanotubes, CO synthesis of cm-sized graphene crystals of ultra-high purity grown during tens of minutes is proposed. The Boudouard reaction serves for the first time to produce individual monolayer structures on the surface of a metal catalyst, thereby providing a chemical vapor deposition technique free from molecular and atomic hydrogen as well as vacuum conditions. This approach facilitates inhibition of the graphene nucleation from the CO/CO mixture and maintains a high growth rate of graphene seeds reaching large-scale monocrystals.