Cryogen-free dilution refrigerator with 14T magnet for high-field studies of quantum materials

量子材料是在实验室中设计的新型系统，它具有足够强的电子相互作用，可以显示超导、关联绝缘态和磁性等量子现象，具有巨大的技术应用。当电子相互作用主导系统的热涨落时，即在毫开尔文温度下，这些现象就会出现。在实验上，这些温度是在稀释冰箱系统中达到的。因此，我们的目标是在LMU的实验能力基础上增加这样一种稀释冰箱，能够达到10mK的基础温度(稳定性低于5mK)，并配备14T超导磁体。该系统没有出现在LMU目前的设备中，将专门用于上述量子材料的研究。这项收购对于确保我们的机构，更准确地说，它的固态物理学主席，在这个及时的主题上的竞争地位至关重要。超高的14T磁场将允许我们为材料引入一个新的量子化能级，从而调节电子相互作用。特别是，这个场将足够高，将各种量子材料的所有电子载流子凝聚到一个单一能级，使电子光谱变得类似于对微扰高度敏感的一维系统。达到这个超量子极限允许出现新的现象，如电荷/自旋密度波和量子霍尔效应。因此，这一冰箱系统将为LMU开启全新的研究轴心。我们将通过48条高度过滤的直流传输线来探测电子对温度和场限制的响应，这些传输线的设计旨在抑制电子的电磁加热，其输出集成在我们的测量设置中，由直流前置放大器和锁定放大器阵列组成。附加的样品旋转器将扩大操作区域，从而可以相对于样品表面任意施加磁场。通过极大地减少加载次数，快速加载机制对于优化我们对该系统的使用至关重要。最后，我们希望购买一个无制冷剂系统，这既是因为它使用简单，因为我们计划允许LMU的几个主席以及慕尼黑量子谷倡议使用这些设备，也是为了考虑到液氦价格不断上涨而允许的长期经济。

Quantum materials are novel systems, engineered in laboratories, which host strong enough electronic interactions to display quantum phenomena such as superconductivity, correlated insulating states and magnetism with tremendous technological applications. These phenomena emerge when the electronic interaction dominate over the thermal fluctuations of the system, i.e. at milliKelvin temperatures. Experimentally, these temperatures are reached in dilution refrigerator systems. Consequently, we aim to add such a dilution refrigerator, capable of a base temperature of 10 mK (and stability below 5mK) and equipped with a 14T superconducting magnet, to the LMU’s experimental capabilities. This system, absent from the current apparatus of the LMU, will be dedicated to the study of said quantum materials. This acquisition is paramount to secure a competitive position for our institution, and more precisely its Chair of Solid State Physics, on this timely subject. The ultra-high 14T magnetic field will allow us to introduce a new quantizing energy scale to the material, and thus to tune the electronic interaction. In particular, this field will be high enough to condense all the electronic carriers of a variety of quantum materials into a single energy level, causing the electronic spectrum to become analogous to a one-dimensional system which is highly sensitive to pertubations. Attaining this ultra-quantum limit permits the emergence of novel phenomena such as charge/spin density waves and quantum Hall effect. This refrigerator system will thus open completely new axis of research at the LMU. We will probe the electronic response to the temperature and field constraints through 48 highly-filtered DC transmission lines designed to suppress electromagnetic heating of the electrons with an output integrated in our measurement setup made of an array of DC pre-amplifiers and lock-in amplifiers. The additional sample rotator will expand the operational area, whereby the magnetic field can be applied arbitrary with respect to the sample surface. The fast loading mechanism is crucial to optimize our usage of this system by greatly reducing loading times. Finally, we wish to buy a cryogen-free system both for its simplicity of usage, as we plan to grant access to the equipment across several chairs of the LMU as well as the Munich Quantum Valley initiative, and for the long-term economies it permits in light of the ever increasing price of liquid helium.