Majorana and Dirac fermion excitations in La0.15Sm0.85MnO3+δ, controlled by external magnetic field

The possibility of excitation of Majorana and massless Dirac fermions in self-doped manganites controlled by an external magnetic field is established. It is shown that in the ZFC mode of magnetization measurement, the excitation of Majorana fermions dominates, while in the FC mode the main contribution to the “supermagnetization” of the sample is made by the excitation of Dirac fermions. During remagnetization of La0.15Sm0.85MnO3+δ manganites at 4.2 K, the single and double cone-shaped features of M(H) were found near H = 0 in the magnetization reversal isotherms. These peculiarities of magnetization demonstrate the evolution of the Dirac fermions magnetic excitations at quantum phase transitions in the 2D Dirac semimetal, induced by the merging and splitting of two Dirac points. The evolution of thermal excitation of two Majorana zero modes in the first and second Landau band with an increase in the strength of the external magnetic field was also studied. Аn alternating permutation of the spiky double peaks and truncated hill features of the magnetization M(T) in La0.15Sm0.85MnO3+δ may be explained by the existence of two well-known in the literature hidden states CSL1 and CSL2 of the chiral quantum spin liquid in this material.