Effect of external factors on magnetism of fluctuating low-dimensional electron and spin correlations in frustrated manganites La$_{1-y}$Sm$_{y}$MnO$_{3+\delta}$ ($y$ = 0.85, 1.0)

In this work, we studied the effect of external influences on the temperature dependences of the magnetization of frustrated manganites La$_{1-y}$Sm$_{y}$MnO$_{3+\delta}$ ($\delta\sim$ 0.1, $y$ = 0.85, 1.0). The two sharp peaks $M(T)$ of different intensities found in both samples at close temperatures $T_1$ and $T_2$ just above the critical temperature $T_c$ of the phase transition to the coherent superconducting state correspond to the Lindhard divergence $\chi_{L}(q_{nest})$ of the temperature dependence of the paramagnetic susceptibility of stripe-like 1D electron / spin correlations modulated with wave vectors $q_{nest1}=2k_{F1}$ and $q_{nest2}=2k_{F2}$. The appearance and evolution of the features of magnetization with increasing field are explained by the formation in ab planes with complete nesting of the electron-hole sections of the Fermi surface of spatial modulation of electronic and magnetic properties in the form of fragments of two fluctuating quasi-one-dimensional charge / spin density waves incommensurate with a crystal lattice with wave vectors $\mathbf{q}_{1}\parallel a$ and $\mathbf{q}_{2}\parallel b$ directions. It is assumed that the strong dependence of the magnetization of fluctuating 1D CDW / SCW correlations on external influences is caused by the close proximity of the properties of the samples to the quantum critical point.