Macroscopic ground-state degeneracy and magnetocaloric effect in the exactly solvable spin-1/2 Ising–Heisenberg double-tetrahedral chain

Highlights: • The exactly solvable spin-1/2 Ising–Heisenberg double-tetrahedral chain is presented. • The ground-state degeneracy and magnetocaloric effect in the model are examined. • The cooling capability of the model is illustrated. • macroscopic degeneracies are confirmed by multiple-peak structures of the specific heat and entropy. - Abstract: The ground-state degeneracy and magnetocaloric effect in the spin-1/2 Ising–Heisenberg double-tetrahedral chain are exactly investigated. It is demonstrated that the zero-temperature phase diagram involves two classical and two quantum chiral phases with distinct degrees of the macroscopic degeneracy. Different macroscopic degeneracies observed in the latter phases and at individual ground-state phase transitions are confirmed by multiple-peak dependencies of the specific heat and entropy on the magnetic field. The cooling capability of the model is well illustrated by the magnetic-field variations of the isothermal entropy change, temperature isotherms and the magnetic Grüneisen parameter.