单晶铁磁LaCrGe$_3$中电子辐照诱导无序对居里温度的增强
Enhancement of the Curie temperature in single crystalline ferromagnetic LaCrGe$_3$ by electron irradiation-induced disorder
AI总结：
通过低温电子辐照在LaCrGe$_3$单晶中引入点状无序，发现居里温度从约90 K升至近100 K，并归因于无序引起的态密度峰展宽增强了费米能级处的态密度。
摘要：
LaCrGe$_3$作为一种铁磁材料中量子相变研究的潜在候选者而受到关注。施加压力会通过发展出一种新的磁相来避免量子临界点。有研究提出，无序可能提供通往量子临界点的另一条途径。我们使用低温2.5 MeV电子辐照在LaCrGe$_3$单晶中诱导相对少量的点状无序。辐照导致所有温度下的电阻率增加，但偏离了马蒂森定则。霍尔效应测量表明，电子辐照不会引起载流子密度的任何可检测变化。出乎意料的是，居里温度$T_{\ ext{FM}}$随着无序度的增加而升高，从原始样品中的约90 K增加到重度辐照样品中的近100 K，并且在更高剂量下趋于饱和。尽管这一效应的机制尚不完全清楚，但我们得出结论，它不能由电子辐照引起的有效“掺杂”或“压力”所致。我们提出，无序引起的态密度$D(E)$中位于费米能$E_F$以下$E_p=E_F-0.25$ eV处的尖锐峰展宽，导致$D(E_F)$增加，从而增强了这一巡游铁磁体中的$T_\ ext{FM}$。
英文摘要：
LaCrGe$_3$ has attracted attention as a potential candidate for studies of quantum phase transitions in a ferromagnetic material. The application of pressure avoids a quantum critical point by developing a new magnetic phase. It was suggested that the disorder may provide an alternative route to a quantum critical point. We used low-temperature 2.5 MeV electron irradiation to induce relatively small amounts of point-like disorder in single crystals of LaCrGe$_3$. Irradiation leads to an increase of the resistivity at all temperatures with some deviation from the Matthiessen rule. Hall effect measurements show that electron irradiation does not cause any detectable change in the carrier density. Unexpectedly, the Curie temperature, $T_{\text{FM}}$, \emph{increases} with the increase of disorder from approximately 90 K in pristine samples up to nearly 100 K in the heavily irradiated sample, with a tendency towards saturation at higher doses. Although the mechanism of this effect is not entirely clear, we conclude that it cannot be caused by effective ``doping" or ``pressure" due to electron irradiation. We suggest that disorder-induced broadening of a sharp peak in the density of states, $D(E)$, situated at $E_p=E_F-0.25$ eV below the Fermi energy, $E_F$, causes an increase in $D(E_F)$, leading to an enhancement of $T_\text{FM}$ in this itinerant ferromagnet.
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