Mnemonics is a collection of special techniques and methods that facilitate the memorization of necessary information and increase the amount of memory by forming associations (links): replacing abstract objects and facts with concepts and representations that have a visual, audial or kinesthetic representation, linking objects with already existing information in memory of various types Modifications to simplify memorization.
Also the term "mnemonics" (an analogue of the pictogram) is used as a designation of visualization (in the form of an image, a set of symbols or objects) of an object, subject or phenomenon that describes it fully and facilitates its memorization or identification.
The technique of mnemonics facilitates memorization in individual cases (where invented artificial associations are fixed during memorization easily and quickly). However, in some cases the incorrect application of the mnemonics can also have a direct effect on the substitution of meaningful (logical) memorization by mechanical memorization.
The term "mnemonic" is originally a Greek word meaning "of memory, or relating to memory". In its modern sense, mnemonic systems provide possible mechanics , techniques or strategies consciously used to improve memory in general and to facilitate the retrieval of information from the long term memory in particular. As you have rightly observed, mnemonics can contribute to language learning, especially in the area of vocabulary learning and there is a rich body of research available on the issue. In point of fact, the following links reflect some of the the relevant information, which can hopefully shed light on what you are looking for.