High-energy cosmic-ray electrons and positrons (CREs), which lose energy quickly during their propagation, provide a probe of Galactic high-energy processes and may enable the observation of phenomena such as dark-matter particle annihilation or decay. The CRE spectrum has been measured directly up to approximately 2 teraelectronvolts in previous balloon- or space-borne experiments, and indirectly up to approximately 5 teraelectronvolts using ground-based Cherenkov γ-ray telescope arrays. Evidence for a spectral break in the teraelectronvolt energy range has been provided by indirect measurements, although the results were qualified by sizeable systematic uncertainties. Here we report a direct measurement of CREs in the energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the Dark Matter Particle Explorer (DAMPE) with unprecedentedly high energy resolution and low background. The largest part of the spectrum can be well fitted by a 'smoothly broken power-law' model rather than a single power-law model. The direct detection of a spectral break at about 0.9 teraelectronvolts confirms the evidence found by previous indirect measurements, clarifies the behaviour of the CRE spectrum at energies above 1 teraelectronvolt and sheds light on the physical origin of the sub-teraelectronvolt CREs.

Ni-Mn-In-Co single-crystalline particles for magnetic shape memory composites Appl. Phys. Lett. 95, 152503 (2009); 10.1063/1.3249585Entropy change and effect of magnetic field on martensitic transformation in a metamagnetic Ni-Co-Mn-In shape memory alloy

The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 1 / 2 years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at~300 GeV found by previous experiments and reveals a softening at~13.6 TeV, with the spectral index changing from~2.60 to~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

We study the electronic structures and magnetic properties of Mn 2 CoZ ͑Z =Al,Ga,In,Si,Ge,Sn,Sb͒ compounds with Hg 2 CuTi-type structure using first-principles full-potential linearized-augmented plane-wave calculations. It is found that the compounds with Z = Al, Si, Ge, Sn, and Sb are half-metallic ferrimagnet. Experimentally, we successfully synthesized the Mn 2 CoZ ͑Z =Al,Ga,In,Ge,Sn,Sb͒ compounds. Using the x-ray diffraction method and Rietveld refinement, we confirm that these compounds form Hg 2 CuTi-type structure instead of the conventional L2 1 structure. Based on the analysis on the electronic structures, we find that there are two mechanisms to induce the minority-spin band gap near the Fermi level, but only the d-d band gap determines the final width of the band gap. The magnetic interaction is quite complex in these alloys. It is the hybridization between the Mn͑C͒ and Co atom that dominates the magnitude of magnetic moment of the Co atom and the sign of the Mn͑B͒-Co exchange interaction. The Mn 2 CoZ alloys follow the Slater-Pauling rule M H = N V − 24 with varying Z atom. It was further elucidated that the molecular magnetic moment M H increases with increasing valence concentration only by decreasing the antiparallel magnetic moment of Mn͑C͒, while the magnetic moments of Mn͑B͒ and Co are unaffected.