Pulsed field facility in Dresden: Magnet technology and some recent ultrasonic results

The Dresden High Magnetic Field Laboratory (HLD) is a user facility which provides external users with the possibility of performing diverse experiments in pulsed magnetic field. Various experimental techniques, such as electrical transport, magnetization, ultrasound and magnetic-resonance measurements are available or are under installation at the HLD [1]. A particular feature of the laboratory is a nearby free-electron laser facility which enables high-field infrared spectroscopy in pulsed magnetic fields.
A 50 MJ modular capacitor bank with a maximum charging voltage of 24 kV is used to energize the pulsed magnets at the HLD. At present, a variety of pulsed magnets are in operation in the laboratory. I report on current status of the pulsed magnet program and recent progress at the HLD. I consider various issues of design, fabrication, and performance of the non-destructive pulsed magnets. Further magnet-technology developments and the route to 100 T are discussed.
In the second part of my talk I will present some ultrasonic results obtained at the HLD. This includes a magneto-acoustic study of the quantum S = 1 spin-chain magnet NiCl2-4SC(NH2)2 (DTN) near the quantum critical points and some recent ultrasonic results for CdCr2O4, a geometrically frustrated magnet with a metamagnetic phase transition at 28 T followed by a very wide magnetization plateau with one half of the full moment of S = 3/2 Cr3+. I discuss a possible application of the infrared radiation produced by next-door free electron lasers for photoacoustic spectroscopy.