a Curie-Weiss law $H/M$ (emu$^{-1}$.mol)$=-0.195 + 0.382~T$ for $T>1.5$ K. []{data-label="fig_MT_HT"}](Plot_YTO_MT_HT.pdf){width="7.0cm"}

Figure \[fig\_MT\_HT\] shows the magnetization measured in a small field as a function of temperature up to 4 K for all the samples. Above 1.5 K, the susceptibility follows a Curie-Weiss law (See inset of figure \[fig\_MT\_HT\]), consistent with previous results above 2 K [@Bramwell01; @Hodges01; @Yasui03; @Thompson11a]. Some differences are obtained between the field orientations. They are mainly due to different demagnetizing effects depending on the shape of the sample even if a small anisotropy is expected [@Hayre13].

Below 1.5 K, the susceptibility continues to increase with decreasing temperature but deviates from the Curie-Weiss law. Then at 250 mK for the powder (165 mK for the single crystal), the magnetization $M$ increases abruptly and reaches a plateau at low temperature.

It is worth noting that the magnitude of $M/H$ (which can be considered as the susceptibility in such a low field) on the plateau is larger for samples with the smaller demagnetizing factors, as expected, and is in the range of $1/N$. In particular, preliminary measurements were performed on a roughly parallelepipeded crystal, along its long direction which corresponds to an arbitrary crystallographic direction. In that case, the 