Magnetic phase diagram of HoB12

Abstract We have investigated the magnetic phase diagram of HoB 12 by specific heat measurements. The specific heat in zero field exhibits a very steep increase at the Neel temperature of T N ≈7.4 K, but its maximum is reached only at a lower temperature ( T M ≈6.6–6.8 K). However, no hysteresis was found and also entropy calculations have not shown any jump at T N . With applied magnetic field up to 8 T specific heat measurements indicate three magnetic phases in the B – T diagram below T N . The origin of the complex phase diagram is discussed.