Magnetic-susceptibility measurements, nuclear magnetic resonance (NMR) of B11, and electron magnetic-resonance (EMR) spectra of YCo3B2 were measured as a function of the temperature. The temperature dependence of the magnetic susceptibility showed a lambda-shaped anomaly at 150K. Whereas upon cooling, a shift in the resonance position of the NMR and EMR spectra is observed at 150K, marking the emergence of an internal magnetic field. The quadrupolar splitting of the NMR lines showed a marked discontinuity at 150K. The (T1T)−1∕2 values were found to be independent of temperature for T>175K, and to increase sharply upon cooling for T<150K. The intensity of the EMR line which is independent of temperature for T>160K is also found to increase markly upon cooling below 150K. All these effects are discussed and it is proposed that YCo3B2 undergoes a magnetic ordering phase transition at 150K.

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